The aim of this study was to investigate the actions of the anti-malignant hyperthermia drug dantrolene-sodium on contractions of myometrium isolated from rat. Myometrium strips were obtained from rats after killing by servical dislocation and suspented in a double-jacketed organ bath containing Krebs solution at 37°C, continuously gassed with %5 CO₂+%95 O₂. After development of spontaneous contractions under one gram resting tension oxytocin (65 mU/L) prostaglandin F2α (1 µM), KCl (20 mM) or dantrolene-sodium (10-30µM) was applied. The effects of these agents on mean peak amplitude and frequency of contractions were evaluated by 10 minute periods, pantrolene sodium significantly inhibited the peak amplitude of oxytocin and prostaglandin F2&alpha-induced (p<0.05) but not KCl induced (p>0.05)contractions in a dose dependent manner. In conclusion, dantrolene-sodium inhibits contractions induced by oxytocin and prostaglandin F2α possible by inhibiting Ca⁺² release from intracellular stores.