Firstly built wooden in 1465. During the reign of Radziwiłł family in Siemiatycze turned into Protestant Church. Present one is in renaissance-baroque style, it has three aisles, shape of basilica, and it was built in 1627-37 from the Lew Sapieh foundation. The whole equipment of the temple is from XVIII century. Main altar was created by Warsaw artists and decorated with sculptures of B. Bernartowicz. The presbytery vaulting  is covered with artistic decoration made of shaped bars which are put in the configuration of circles, ovals, squares, stars, hearts and pervading tetraleaves.