Evidence about sex and gender differences in pain and analgesia has been gathered rapidly during the past decade. A number of studies have demonstrated a higher prevalence of pain states and greater pain sensitivity among women compared with men. Sex hormones influence pain sensitivity. Activity of cytochrome P450 in female is greater than in male and this suggested that drugs are more rapidly metabolized in female than in male. Analgesic effect of pentazocine is reported to be more potent in male than in female. These data strongly suggested that males and females may have different pain modulatory circuits. Continued research at the genetic and receptor levels may support to develop gender-specific therapies.