Abstract: The effect of fentanyl injected into rat paw on paw-pressure threshold was observed with a self-made and improved paw-pressure technique in the present paper. The results from the peripheral analgesic study show that local inj- ction of fentanyl into rat paw produces significant inhibition of inflamm- atory hyperalgesia but has no effect on normal paw. The results suggest that peripheral analgesic effect of fentanyl occurs under conditions of inflammation and accompanying pain but not on normal rats.

Key words: paw-pressure technique, hyperalgesia, peripheral analgesic effect, fentanyl