Exhibit 31-a

Certification
of Principal Executive Officer Required by Exchange Act Rule 13a-14(a)

I, Robert E.
Switz, the Chief Executive Officer of ADC Telecommunications, Inc., certify that:

|1. |  | I
have reviewed this quarterly report on Form 10-Q of ADC Telecommunications, Inc.;
|-- |  | -----------------------------------------------------------------------------------

|2. |  | Based
on my knowledge, this report does not contain any untrue statement of a  material fact or
omit to state a material fact necessary to make the statements  made, in light of the
circumstances under which such statements were made, not  misleading with respect to the
period covered by this report;
|-- |  | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

|3. |  | Based on my knowledge, the financial statements, and other financial information
included in this report, fairly present in all material respects the financial
condition, results of operations and cash flows of the registrant as of, and
for, the periods presented in this report.
|-- |  | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

|4. |  | The registrants other certifying officer and I are responsible for
establishing and maintaining disclosure controls and procedures (as defined in
Exchange Act Rules 13a-15(e) and 15d-15(e)) for the registrant and have:
|-- |  | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

|a) |  | Designed such disclosure controls and procedures, or caused such disclosure controls and
procedures to be designed under our supervision, to ensure that material information
relating to the registrant, including its consolidated subsidiaries, is made known to us
by others within those entities, particularly during the period in which this report is
being prepared;
|-- |  | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

|b) |  | Evaluated the effectiveness of the registrants disclosure controls and procedures
and presented in this report our conclusions about the effectiveness of the disclosure
controls and procedures, as of the end of the period covered by this report based on such
evaluation; and
|-- |  | -----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

|c) |  | Disclosed in this report any change in the registrants internal control over
financial reporting that occurred during the registrants most recent fiscal quarter
(the registrants fourth fiscal quarter in the case of an annual report) that has
materially affected, or is reasonably likely to materially affect, the registrants
internal control over financial reporting.
|-- |  | -----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

|5. |  | The registrants other certifying officer and I have disclosed, based on
our most recent evaluation of internal control over financial reporting, to the
registrants auditors and the audit committee of the registrants
board of directors (or persons performing the equivalent function):
|-- |  | ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

|a) |  | All significant deficiencies and material weaknesses in the design or operation of
internal control over financial reporting which are reasonably likely to adversely affect
the registrants ability to record, process, summarize and report financial
information; and
|-- |  | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

|b) |  | Any fraud, whether or not material, that involves management or other employees who have a
significant role in the registrants internal control over financial reporting.
|-- |  | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------

Date: 6/8/05

| | /s/
Robert E. Switz       Robert E. Switz
       Chief Executive Officer
| | ------------------------------------------------------------------------