The Church of the Assumption of the Blessed Virgin Mary (Polish: Kościół Wniebowzięcia Najświętszej Marii Panny), known colloquially as the St. Mary's Church (Polish: Kościół Mariacki), is a Brick Gothic church adjacent to the Main Market Square in Kraków, Poland. Built in the 14th century, its foundations date back to the early 13th century and serve as one of the best examples of Polish Gothic architecture. Standing 80 m (262 ft) tall, it is particularly famous for its wooden altarpiece carved by Veit Stoss (Wit Stwosz). Some of its monumental polychrome murals were designed by Poland's leading history painter, Jan Matejko (1838–1893). In 1978, it became a UNESCO World Heritage Site alongside the Historic Centre of Kraków.

On every hour, 24 hours a day, 365 days a year, a trumpet signal—called the Hejnał mariacki—is played from the top of the taller of Saint Mary's two towers. The plaintive tune breaks off in mid-stream, to commemorate a famous 13th-century trumpeter who was shot in the throat while sounding the alarm before a Mongol attack on the city. The noon-time hejnał is heard across Poland and abroad broadcast live by Polish Radio Jedynka.

Saint Mary's Basilica also served as an architectural model for many of the churches that were built by the Polish diaspora abroad, particularly those like Saint Michael's and Saint John Cantius in Chicago, designed in the Polish Cathedral style.

The church is familiar to many English-speaking readers from the 1928 book The Trumpeter of Krakow by Eric P. Kelly.