Sodium salicylate, an anti-inflammatory agent, was examined for its effects on the heat shock response in cultured human cells. Salicylate activation of DNA binding by the heat shock transcription factor (HSF) was comparable to activation attained during heat shock. However, sodium salicylate did not induce heat shock gene transcription even though the HSF was bound in vivo to the heat shock elements upstream of the heat shock protein 70 (Hsp 70) gene. These results reveal that activation of the heat shock transcriptional response is a multistep process. Modulation of extracellular pH augments sensitivity to salicylate-induced activation of HSF.