Using Fura-2AM, a fluorescent Ca2+ indicator, we have shown for the first time that the sigma-1 receptor antagonist - neuroleptic chlorpromazine - significantly inhibits the store-dependent Ca2+entry induced by immunomodulators glutoxim as well as molixan and endoplasmic reticulum Са2+-ATPase inhibitors thapsigargin and cyclopiazonic acid in rat peritoneal macrophages. The results suggest the involvement of sigma-1 receptors in the regulation of store-dependent Ca2+ entry in macrophages.