Exhibit 14.1  Cubist Employee Policy
  
  CODE OF CONDUCT AND ETHICS  Cubist Pharmaceuticals, Inc., and its affiliates (together Cubist
or the Company) is committed to conducting business with a high degree of
integrity.  This Code of Conduct and
Ethics is your guide to applicable laws and regulations as well as key Cubist policies
and procedures that provide guidance for conducting business in a legal and
ethical manner.  All employees and Directors must act in accordance with the Code and
seek to avoid even the appearance of improper behavior.  The Code should also be provided to and
followed by consultants to the Company. Violations of the standards in this
Code will subject you to disciplinary action up to and including termination.  The Code does not cover every situation that may arise but establishes
important standards, principles, and rules to guide the actions of all
employees and Directors.   If you are
uncertain whether an action may violate the Code or another Cubist policy, you
should seek advice before taking
action.  A good basis for deciding when to get advice is to ask yourself whether
the conduct might be embarrassing to the Company or the persons involved if the
details were fully disclosed to the public by the media. Since we cannot anticipate every situation
that will arise, it is important that we have a way to approach a new question
or problem.  These are the steps to keep
in mind:  ·Make sure you
have all the facts.  In order to reach the right solutions, we must
be as fully informed as possible.  ·Ask yourself:
What specifically am I being asked to do? Does it seem unethical or improper?  This will enable you to focus on the specific
question you are faced with and the alternatives you have.  Use your judgment and common sense; if
something seems unethical or improper, it probably is.  ·Clarify your
responsibility and role.  In most
situations, there is shared responsibility. 
Are your colleagues informed?  It
may help to get others involved and discuss the problem.  ·Discuss the
problem with your supervisor.  This
is the basic guidance for all situations. 
In many cases, your supervisor will be more knowledgeable about the
question and will appreciate being brought into the decision-making
process.  Remember that it is your
supervisors responsibility to help you solve problems.  ·Seek help
from Company resources.  In the case
where it may not be appropriate to discuss an issue with your supervisor or
where you do not feel comfortable approaching your supervisor with your
question, discuss it with any director-level or higher employee in the Law
Department or the Chief Compliance Officer.  ·Always ask
first, act later. If you are unsure
of what to do in any situation, seek guidance before you act.  Policy Owner: Compliance
  
  Effective: September 2008


Employees must
promptly report any violations or suspected violations of this Code or any
illegal activities they observe.  Reports may be made in confidence and
without fear of retaliation.  If you know or reasonably
believe that there has been a violation of this Code or any kind of unlawful
behavior, you must report that information to your supervisor or a more senior
manager or, if your manager will not or cannot help or is part of the problem,
to any director-level or higher employee in the Law Department or the Chief
Compliance Officer.     You may also call
the Companys internal Compliance Helpline at 781-860-8600.  If you prefer, you may also submit reports  anonymously,
through the Companys externalCorporate
Responsibility Hotline at 1-888-690-3869 or on the web at
www.silentwhistle.com.  Directors must report violations or suspected violations of the Code to
the Chairman, Lead Director or Chairman of the Governance Committee of the Board
of Directors.  Section 1.Compliance
with Laws, Rules and Regulations  Obeying the law, both in letter and in spirit, is the foundation on
which this Companys ethical standards are built.  All employees and Directors must respect and
obey the laws of the jurisdictions in which we operate.  If a law conflicts with a policy in this
Code, you must comply with the law; however, if a local custom or policy
conflicts with this Code, you must comply with the Code.  Although not all employees and Directors are
expected to know the details of these laws, it is important to know enough to
determine when to seek advice.  The Company holds information and training sessions and has put in
place various policies and procedures in order to promote compliance with laws,
rules and regulations, including insider-trading laws.  Each department head is responsible for
ensuring that his/her employees attend all mandatory training sessions that are
related to compliance with laws, rules and regulations applicable to
his/her job functions.  Section 2.Conflicts
of Interest  All employees and Directors are expected to make decisions in the best
interest of the Company and not for personal gain, and therefore are required
to avoid conflicts of interest. Conflicts of interest may not always be
clear-cut and you should seek advice if you are unsure whether a situation
poses a conflict of interest.  A conflict of interest exists when a persons private interest interferes
in any way with the interests of the Company. 
A conflict can arise when an employee or Director takes actions or has
interests that may make it difficult to perform his or her Company
responsibilities objectively and effectively. 
Conflicts of interest may also arise when an employee or Director, or
members of his or her family, receives personal benefits as a result of his or
her position in the Company.  Loans to,
or guarantees of obligations of, employees or Directors and their family
members may create conflicts of interest.  2


It is almost always a conflict of interest for a Company employee to
work simultaneously for a competitor, customer, supplier, or vendor.  Employees are not allowed to work for a
competitor in any capacity, including as a consultant or board member.  The best policy is to avoid any direct or
indirect business connection with customers, suppliers, or competitors, except
on the Companys behalf.  Directors must comply with the Conflict of Interest provisions set
forth in the Amended and Restated Corporate Governance Guidelines.  Section 3.Insider
Trading  Employees and Directors who have access to confidential information are
not permitted to use or share that information for stock trading purposes or
for any other purpose except the conduct of the Companys business.  All non-public information about the Company
should be considered confidential information. 
To use non-public information for personal financial benefit or to tip
others who might make an investment decision on the basis of this information
is not only unethical but also illegal. 
If you have any questions, please refer to the Companys Policy on
Insider Trading and Confidentiality, and then ask any director-level or higher
employee in the Law Department.  Section 4.Corporate
Opportunities  Employees and Directors are prohibited from exploiting for their
personal advantage opportunities that are discovered through the use of
corporate property, information, or position without the consent of the Board
of Directors.  No employee or Director
may use corporate property, information, or position for personal gain, and no
employee or Director may compete with the Company directly or indirectly.  Employees and Directors owe a duty to the
Company to advance its legitimate interests when the opportunity to do so
arises.  Section 5.Competition
and Fair Dealing  We seek to outperform our competition fairly and honestly.  We seek competitive advantages through
superior performance, never through unethical or illegal business
practices.  Stealing proprietary
information, possessing trade secret information that was obtained without the
owners consent, or inducing such disclosures by past or present employees of
other companies is prohibited.  Each
employee and Director should endeavor to respect the rights of and deal fairly
with the Companys customers, suppliers, competitors, vendors, and their
employees.  No employee or Director
should take unfair advantage of anyone through manipulation, concealment, abuse
of privileged information, misrepresentation of material facts, or any other
intentional unfair-dealing practice.  Drug development is highly competitive, and it is the policy of the
Company to compete aggressively, but fairly.  All employees are expected to protect the
integrity of the research and development process by ensuring that all
research, non-clinical, and clinical development activities are conducted with
the highest ethical standards.  A major part of this commitment to compete fairly is a commitment to
abide fully by the antitrust laws.  In
general, these complex laws prohibit any form of agreement or understanding 
whether formal, informal, express, or implied  that unreasonably reduces
competition and  3


business rivalry.  Our commitment
in this regard also prohibits any unfair or untrue disparagement of a Company
competitor.  All suppliers, vendors and contractors should be selected on the basis
of written competitive bids if the amount of the services or goods to be
provided is significant.  Employees
should check with Purchasing to determine if a competitive bid is required.  The purpose of business entertainment and gifts in a commercial setting
is to create good will and sound working relationships, not to gain unfair
advantage with customers.  Gifts or
entertainment should not ever be offered, given, provided to any customer,
supplier, or vendor, or accepted from any customer, supplier, or vendor by any
Company employee or Director, or family member of an employee or Director
unless it: (1) is not a cash gift, (2) is consistent with customary
business practices, (3) is not excessive in value, (4) cannot be
construed as a bribe or payoff, (5) does not violate any laws or
regulations, and (6) is offered in compliance with applicable Company
policies and procedures.  It is the policy of the Company to comply with health care fraud and
abuse laws.  This includes Federal and
State anti-kickback laws that prohibit offering or giving kickbacks or other
improper inducements to healthcare professionals, which includes anyone who may
be in a position to purchase or prescribe or to arrange for or recommend the
purchase or prescription of the Companys products.  Any arrangements with healthcare
professionals, including, for example, gifts, research grants, and business
courtesies, must comply with applicable laws, Company policies, and procedures,
which are available from the Compliance Department.  If you are uncertain about offering or accepting a gift or business
entertainment, you should seek advice before taking
any action.  Section 6.Discrimination
and Harassment  The diversity of the Companys employees is a tremendous asset.  We are firmly committed to providing equal
opportunity in all aspects of employment and will not tolerate any
discrimination or harassment of any kind. Please refer to Cubists Policy
Against Sexual Harassment in the Workplace for additional information and
guidance.  Section 7.Health
and Safety  The Company strives to provide each employee with a safe and healthful
work environment.  Each employee has
responsibility for maintaining a safe and healthy workplace for all employees
by following safety and health rules and practices and reporting
accidents, injuries and unsafe equipment, practices or conditions.  The Company will not tolerate violence and threatening behavior.  Employees should report to work in condition
to perform their duties, free from the influence of illegal drugs or
alcohol.  The Company will not tolerate
the use of illegal drugs in the workplace or on the Companys property.  Please see the Companys policies for further
guidance.  4


Section 8.              Record-Keeping  All business records must be recorded accurately and truthfully.  The Company follows the accepted accounting rules and
controls set forth by the U.S. Securities and Exchange Commission and the
Financial Accounting Standards Board. 
The Company requires honest and accurate recording and reporting of
information in all circumstances, and without exception.  The Company requires that its certified
public accountants have access to any and all information necessary for them to
conduct audits properly.  Business expense accounts must be documented and recorded
accurately.  If you are not sure whether
a certain expense is legitimate, ask your supervisor or the Accounts Payable
Supervisor,Accounting Manager or Director of Accounting.   They can also provide you with rules and
guidelines.  All of the Companys books, records, accounts and financial statements
must be maintained in reasonable detail, must appropriately reflect the Companys
transactions and must conform both to applicable legal requirements and to the
Companys system of internal controls. Unrecorded or off the books funds or
assets should not be maintained unless permitted by applicable law or
regulation and approved in writing by the Chief Financial Officer.  Business records and communications often become public, and should not
contain exaggeration, derogatory remarks, guesswork, or inappropriate
characterizations of people and companies. This applies equally to e-mail,
internal memos, and formal reports.  Records should always be retained or
destroyed according to the Companys record retention policies.  In
accordance with those policies, in the event of litigation or governmental
investigation, threatened or known, please consult with a director-level or
higher employee in the Law Department.  Section 9.Confidentiality  Employees and Directors must maintain the confidentiality of
confidential information entrusted to them by the Company, including
confidential information that the Company has received from a third party,
except when disclosure is authorized by a director-level or higher employee in
the Law Department, or required by laws or regulations.  Confidential information includes all
non-public information that might be of use to competitors, or harmful to the
Company or its customers, if disclosed. 
It also includes information that suppliers, customers, and other third
parties have entrusted to the Company. 
The obligation to preserve confidential information continues even after
employment ends.  Section 10.Protection
and Proper Use of Company Assets  All employees and Directors should endeavor to protect the Companys
assets and ensure their efficient use. 
Theft, carelessness, and waste have a direct impact on the Companys
profitability.  Any suspected incident of
fraud or theft should be immediately reported for investigation.  Company equipment should not be used for
non-Company business, though incidental personal use may be permitted.  The obligation of employees and Directors to
protect the Companys assets includes its proprietary information.  Proprietary information includes intellectual
property such as trade secrets, patents, trademarks, and copyrights, as well as
business, marketing and service plans, engineering and manufacturing ideas,
designs, databases, records, salary information and any unpublished financial
data and reports.  Unauthorized use or
distribution of this information would violate Company policy.  It could also be illegal and result in civil
or  5


even criminal penalties.  Please see the Companys policies on information
technology usage and confidentiality for further guidance.  **Section 11.  Political Activities and Engagement with
Government Personnel**  To foster active responsible citizenship at the national, state and
local level, Cubist supports and encourages employee participation in
traditional political activities during non-work time.  Such activities may include civic projects,
supporting candidates for elective office or participation in public issue
campaigns.  An employees involvement and
participation in civic affairs, the political process or legislative and
executive branch matters must be on his or her own time and at his or her own
expense, not interfere with work responsibilities, not use corporate property,
and not be as a representative of Cubist. 
The exceptions to this are employees who are specifically designated by
the Vice President of Government Affairs or General Counsel.  Subject to strict legal and policy
limitations, Cubist may also be involved in the political process through a
Political Action Committee (PAC).  It is
imperative that all political activities be conducted in strict compliance with
all applicable laws, regulations and corporate policies, and in accordance with
the highest standards of honesty and integrity. If you have any questions
regarding proposed political activity, check with the Vice President of
Government Affairs.  In addition, the U.S. government has a number of laws and regulations
regarding the provision of business gratuities to U.S. government personnel,
including, for example, employees of Medicare, Medicaid, and the Veterans
Administration. The promise, offer or delivery to an official or employee of
the U.S. government of a gift, favor or other gratuity in violation of these rules would
not only violate Company policy but could also be a criminal offense. State and
local governments, as well as foreign governments, may have similar rules.  The U.S. Foreign Corrupt Practices Act prohibits giving anything of
value, directly or indirectly, to employees of foreign governments (including
doctors and other health care personnel employed by foreign government
agencies) or foreign political candidates in order to obtain or retain
business. It is strictly prohibited to make payments to government employees of
any country.  Section 12.            Misrepresentations and False Statements  Employees and Directors must never make a deliberate misrepresentation
concerning the Company or its business operations.  No employee or Director shall create, or
assist another in creating, a false or misleading entry on the Companys books
or business records.  Section 13.Responding
to Government Requests  It is the Companys policy to cooperate with all reasonable requests
from Governmental agencies concerning the Companys business operations.
Employees and Directors are expected to respond truthfully to Governmental
inquiries.  All government inquiries,
whether initiated by telephone, subpoena, or other request, must be immediately
communicated to a director-level or higher member of the Law Department before
taking any action.  6


Section 14.Waivers
of the Code of Business Conduct and Ethics  While some standards in this Code require strict application and
exceptions or waivers are not allowed, others do allow for waivers.  Any waiver of this Code for Executive
Officers or Directors may be made only by the Board of Directors and will be
promptly disclosed as required by law or Nasdaq regulation.  Employees other than Executive Officers who believe they may merit a
waiver should first consult their supervisor. 
If the supervisor agrees that a waiver is warranted, the supervisor
should forward the request to the Chief Compliance Officer.  The Chief Compliance Officer and CEO will
jointly approve or disapprove the request.  7