A cytological survey of the ovarian nurse cells of 190 species of Diptera belonging to 40 families reveals the presence of banded polytene chromosomes in 16 species belonging to the families Cecidomyidae, Empidae, Dolichopidae,Lonchopteridae, Helomyzidae, Agromyzidae and Tachinidae.In some species the nurse cell chromosomes show the characteristics of the most favorable salivary gland chromosomes in regard to size,spreading and detail of banding pattern.In at least one species, Cerodontha, dorsalis,the banded polytene chromosomes while showing a striking similarity to salivary gland chromosomes as they occur in Drosophila, also reveal incomplete association of the chromatids within the homologous-chromosomes. This suggests a condition intermediate to that found in the endomitotic nurse cells and the salivary glands of Drosophila, and as such may be considered to support the multiple strand concept of salivary gland chromosome. structure.