Saint Mary Cemetery is a Roman Catholic burial ground located at 45th and Penn Avenues in the Central Lawrenceville neighborhood of Pittsburgh, Pennsylvania, USA. It is adjacent of the city's slightly older and much larger Allegheny Cemetery. A chain-link fence separates the two cemeteries.
The 44-acre tract of land was established as a cemetery in 1849 at a cost of $20,000, six years after the founding of the Roman Catholic Diocese of Pittsburgh. As of 2008, it has 100,298 interments.