| | UNITED STATES                      | OMB APPROVAL                     
| | ---------------------------------- | ---------------------------------
| | SECURITIES AND EXCHANGE COMMISSION |                                  
| |                                    | OMB Number: 3235-0381            
| | Washington, D.C. 20549             | Expires: September 30, 2018      
| |                                    | Estimated average burden         
| | FORM 40-F/A                        | hours per response. . . ...429.93

Amendment No.
1

[Check one]



|   |  ̈ | REGISTRATION STATEMENT PURSUANT TO SECTION 12 OF THE SECURITIES EXCHANGE ACT OF 1934   
|-- | - | ---------------------------------------------------------------------------------------
|OR
|   | x | ANNUAL REPORT PURSUANT TO SECTION 13(a) OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934



For the fiscal year ended: December 31,
2017Commission File Number: 001-38141



|Sierra Metals Inc.                                                                                                      
|------------------------------------------------------------------------------------------------------------------------
|(Exact name of Registrant as specified in its charter)                                                                  
|                                                                                                                        
|Not Applicable                                                                                                          
|(Translation of Registrant’s name into English (if applicable))                                                         
|                                                                                                                        
|Canada                                                                                                                  
|(Province or other jurisdiction of incorporation or organization):                                                      
|                                                                                                                        
|1021                                                                                                                    
|(Primary Standard Industrial Classification Code Number (if applicable))                                                
|                                                                                                                        
|Not Applicable                                                                                                          
|(I.R.S. Employer Identification Number (if applicable))                                                                 
|                                                                                                                        
|79 Wellington Street, West, Ste. 2100, Toronto, Ontario M5K 1H1 (416) 366-7777                                          
|(Address and telephone number of Registrant’s principal executive offices)                                              
|                                                                                                                        
|Cogency Global Inc.                                                                                                     
|10 East 40th Street, 10th Floor, New York, NY 10016 (800) 221-0102                                                      
|(Name, address (including zip code) and telephone number (including area code)of agent for service in the United States)



Securities registered or to be registered pursuant to Section
12(b) of the Act.



|Common Shares       |  | NYSE American                            
|------------------- |  | -----------------------------------------
|Title of each class |  | Name of each exchange on which registered



Securities registered or to be registered pursuant to Section
12(g) of the Act.



None



Securities for which there is a reporting obligation pursuant
to Section 15(d) of the Act.



None



For annual reports, indicate by check mark the information filed
with this Form:



Annual
information formxAudited
annual financial statementsx



Indicate the number of outstanding shares of each of the issuer’s
classes of capital or common stock as of the close of the period covered by the annual report.



Common Shares: 163,029,548



Indicate by check mark whether the Registrant
by filing the information contained in this Form is also thereby furnishing the information to the Commission pursuant to Rule
12g3-2(b) under the Securities Exchange Act of 1934 (the “Exchange Act”). If “Yes” is marked, indicate
the file number assigned to the Registrant in connection with such Rule.



Yes ̈ Nox



Indicate by check mark whether the Registrant
(1) has filed all reports required to be filed by Section 13 or 15(d) of the Exchange Act during the preceding 12 months (or for
such shorter period that the Registrant was required to file such reports) and (2) has been subject to such filing requirements
for the past 90 days.



Yesx No ̈



Indicate by check mark whether the registrant is an emerging
growth company as defined in Rule 12b-2 of the Exchange Act.



Emerging
growth companyx



If an emerging growth company that prepares its financial statements
in accordance with U.S. GAAP, indicate by checkmark if the registrant has elected not to use the extended transition period for
complying with any new or revised financial accounting standards† provided pursuant to Section 13(a) of the Exchange Act.



 ̈

Not applicable


















EXPLANATORY NOTE



Sierra Metals Inc.
(the “Company” or “we” or “us”) is a Canadian issuer eligible to file its annual report pursuant
to Section 13 of the Securities Exchange Act of 1934, as amended (the “Exchange Act”), on Form 40-F (“Form
40-F”) pursuant to the multi-jurisdictional disclosure system of the Exchange Act. We are a “foreign private issuer”
as defined in Rule 3b-4 under the Exchange Act. Accordingly, our equity securities are exempt from Sections 14(a), 14(b),
14(c), 14(f) and 16 of the Exchange Act pursuant to Rule 3a12-3.





This Amendment No. 1 to the Company's Form
40-F (“Amendment No. 1”) amends the Company’s Annual Report on Form F-40 for the fiscal year ended December 31,
2017 by refiling Exhibit 99.2, the Company's Audited Consolidated Financial Statements for the year ended December 31, 2017, to
correct the inadvertent omission of the date of the Report of the Company's Independent Auditor that accompanied such Audited Consolidated
Financial Statements. The Company is also refiling Exhibit 23.1, the Consent of the Company's Independent Auditor and Exhibits
31.1, 31.2, 32.1 and 32.2, the Certifications of the Company's Chief Executive Officer and the Company's Chief Financial Officer.
Other than as set forth herein, this Amendment No. 1 does not modify or update any disclosures and makes no changes to the Form
40-F.





1







INDEX TO EXHIBITS





The following Exhibits are being filed
with this Amendment No. 1:



|Consents       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       
|-------------- | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
|               |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       
|23.1           | Consent of PricewaterhouseCoopers LLP                                                                                                                                                                                                                                                                                                                                                                                                                                                 
|               |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       
|Certifications |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       
|               |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       
|31.1           | Certification of Chief Executive Officer pursuant to Rule 13a-14(a) or 15d-14(a) of the Securities Exchange Act of 1934                                                                                                                                                                                                                                                                                                                                                               
|               |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       
|31.2           | Certification of Chief Financial Officer pursuant to Rule 13a-14(a) or 15d-14(a) of the Securities Exchange Act of 1934                                                                                                                                                                                                                                                                                                                                                               
|               |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       
|32.1           | Certification of Chief Executive Officer pursuant to 18 U.S.C. Section 1350 (This Exhibit is furnished herewith, but not deemed "filed" for purposes of Section 18 of the Securities Exchange Act of 1934, as amended, or otherwise subject to liability under that section. Such certification will not be deemed to be incorporated by reference into any filing under the Securities Act or the Exchange Act, except to the extent that we explicitly incorporate it by reference.)
|               |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       
|32.2           | Certification of Chief Financial Officer pursuant to 18 U.S.C. Section 1850 (This Exhibit is furnished herewith, but not deemed "filed" for purposes of Section 18 of the Securities Exchange Act of 1934, as amended, or otherwise subject to liability under that section. Such certification will not be deemed to be incorporated by reference into any filing under the Securities Act or the Exchange Act, except to the extent that we explicitly incorporate it by reference.)





10







|Annual
 Information |                                                                                                     
|------------------- | ----------------------------------------------------------------------------------------------------
|                    |                                                                                                     
|99.2                | Audited Consolidated Financial Statements of Sierra Metals Inc. for the year ended December 31, 2017



11







SIGNATURES



Pursuant to the requirements
of the Exchange Act, the Registrant certifies that it meets all of the requirements for filing this Form 40-F and has duly caused
this amendment to our annual report to be signed on its behalf by the undersigned, thereto duly authorized.



| | SIERRA METALS INC.
| | ------------------
| |                   
| | By:               
| | Name:             
| | Title:            



Date: March 26, 2018