The electron impact mass spectra of some 1-(2-furyl)- and 1-(2-thienyl)-2-(2-benzothiazolyl) ethenes have been recorded and the identity of various ions in the mass spectra established. The compounds examined (1-10) exhibit two main fragmentation routes. On one hand, fragmentation of the furan and thiophene nuclei and the formation of cyclopropenylethyne cations with very significant abundance and on the other hand, fragmentation of the benzothiazole nuclei on characteristic pathways. Compounds 6-10 also show two additional fragmentation routes.