Previous deletion analysis of the Drosophila hsp70 heat-shock promoter has identified a sequence upstream of the TATA box that is required for heat induction. This region contains homology to other heat-shock promoters, and it was proposed that the common sequence is an important element in the regulation of the heat-shock genes. We have constructed sequences similar to the consensus CT-GAA-TTC-AG from synthetic oligonucleotides and placed them upstream of the TATA box of the herpes virus thymidine kinase gene, in place of the normal upstream promoter element. The resultant genes are heat-inducible both in monkey COS cells and in Xenopus oocytes. We conclude that the transcriptional heat-shock response is mediated by some factor that interacts with this sequence.