The compounds K3BiSe3, Rb3BiSe3, and Cs3BiSe3 were synthesized by heating mixtures of Bi2O3 and the respective alkalicarbonate in a stream of hydrogen saturated by selenium at 850 degrees C. Thin crystals of the compounds appear red in transmitted light. They crystallize isostructural with Na3AsS3, space group P2(1)3, lattice constants a = 9.771(5) Angstrom, a = 10.161(3) Angstrom, and a = 10.587(5) Angstrom for K3BiSe3, Rb3BiSe3, and Cs3BiSe3, respectively. The Na3AsS3 structure type is a derivative of the Th3P4 structure type.