Offseason
- December 6, 1990: Zane Smith was signed as a free agent by the Pirates.
- February 4, 1991: Mark Huismann was signed as a free agent by the Pirates.
- March 21, 1991: Esteban Loaiza was signed as an amateur free agent by the Pirates.
- March 29, 1991: Steve Carter was traded by the Pirates to the Chicago Cubs for Gary Varsho.
Read more about this topic: 1991 Pittsburgh Pirates Season