Embryos of 21 temperature-sensitive Drosophila mutants were used to set up 232 primary cultures. From these, 57 cell lines are being subcultured, and we consider 33 of them to be continuous. Nineteen of the 21 mutants are represented in these 57 lines. Four characteristics of each of the continuous lines are described: morphology, ecdysterone response, karyotype, and response to a restrictive temperature. We discuss the potential uses of such cell lines.