The white locus produces one major, though rare, RNA of 2.6 kb, found throughout development. Minor species of lower mol. wt. are also produced. One of these is male specific. Transcription was analysed by Northern blot hybridisation in the wild-type and several mutants: wa, w67c23, we, wsp and zeste. These and the results of S1 mapping reveal the presence of at least four introns. One of these, a micro-intron of 30-50 nucleotides contains the site of copia insertion in the wa mutant.