We studied the effect of bilateral microinjections of selective pharmacological agents modulating glycine receptor activity into the medial preoptic nucleus on sexual behavior of male Wistar rats. Application of the glycine receptor blocker strychnine (20 μM, 2 μl) led to a significant inhibition of both appetitive and consummatory components of sexual behavior, whereas stimulation with glycine (1 mM and 50 μM, 2 μl) had no significant effect.