The neurogenic genes ofDrosophila melanogasterare required for correct separation of neural and epidermal progenitor cells during early embryogenesis. Results from genetic analyses indicate that the neurogenic genes are functionally related. We have studied the spatial distribution of RNA from the neurogenic genesD1, neu, andm4, m5, m7andE(spl)[four genes of theEnhancer of splitcomplex] in various neurogenic mutant embryos by in situ hybridization. An abnormal distribution of RNA from certain of the genes is found in neurogenic mutants, suggesting that at least some of the functional interactions inferred from genetic data take place at the transcriptional level. We discuss these results in relation to the events of early neurogenesis.