Using voltage-clamp technique, the involvement of sigma-1 receptors in immunomodulatory drug glutoxim regulation of Na+ transport in frog skin was investigated. We have shown for the first time that preincubation of the frog skin with sigma-1 receptor antagonists – haloperidol or chlorpromazine – attenuates the stimulatory effect of glutoxim on Na+ transport. The results suggest the possible involvement of the sigma-1 receptors in glutoxim effect on Na+transport in frog skin epithelium.