List of number-one albums of 1991 (Spain)
The following is a list of albums that reached number one in Spain during 1991, according to the Productores de Música de España (PROMUSICAE) official weekly chart. Note that official charts were not consistently published or readily available in earlier years, and this list is based on currently available data and may be incomplete.
- January 7 - Mecano - Aidalai
- January 14 - Mecano - Aidalai
- January 21 - Mecano - Aidalai
- January 28 - Mecano - Aidalai
- February 4 - Mecano - Aidalai
- February 11 - Mecano - Aidalai
- February 18 - Mecano - Aidalai
- February 25 - Mecano - Aidalai
- March 4 - Mecano - Aidalai
- March 11 - Mecano - Aidalai
- March 18 - Mecano - Aidalai
- March 25 - Mecano - Aidalai
- April 1 - Mecano - Aidalai
- April 8 - Mecano - Aidalai
- April 15 - Mecano - Aidalai
- April 22 - Mecano - Aidalai
- April 29 - Mecano - Aidalai
- May 6 - Mecano - Aidalai
- May 13 - Mecano - Aidalai
- May 20 - Mecano - Aidalai
- May 27 - Mecano - Aidalai
- June 3 - Mecano - Aidalai
- June 10 - Mecano - Aidalai
- June 17 - Mecano - Aidalai
- June 24 - Mecano - Aidalai
- July 1 - Mecano - Aidalai
- July 8 - Mecano - Aidalai
- July 15 - Mecano - Aidalai
- July 22 - Mecano - Aidalai
- July 29 - Mecano - Aidalai
- August 5 - Mecano - Aidalai
- August 12 - Mecano - Aidalai
- August 19 - Mecano - Aidalai
- August 26 - Mecano - Aidalai
- September 2 - Mecano - Aidalai
- September 9 - Mecano - Aidalai
- September 16 - Mecano - Aidalai
- September 23 - Mecano - Aidalai
- September 30 - Mecano - Aidalai
- October 7 - Mecano - Aidalai
- October 14 - Mecano - Aidalai
- October 21 - Mecano - Aidalai
- October 28 - Mecano - Aidalai
- November 4 - Mecano - Aidalai
- November 11 - Mecano - Aidalai
- November 18 - Mecano - Aidalai
- November 25 - Mecano - Aidalai
- December 2 - Mecano - Aidalai
- December 9 - Michael Jackson - Dangerous
- December 16 - Michael Jackson - Dangerous
- December 23 - Michael Jackson - Dangerous
- December 30 - Michael Jackson - Dangerous