1. The possible antinociceptive action of GABA A receptor agonist homotaurine, has been studied through a battery of chemical (acetic acid) and thermal (hot plate, tail flick and tail immersion) tests in rats and mice. 2. The aminoacid was used at the following doses 22.25; 55.62 and 111.24 mg/kg i.p. and 50-100 micrograms i.c.v.; and measurements were made at the time of and at 5, 15 and 30 min after drug administration. 3. Homotaurine exhibited a significantly antinociceptive effect in all the above mentioned test except hot plate and when administered i.c.v. in the tail flick test. 4. The antinociceptive effect in the chemical test was dose and time dependent. 5. In the tail immersion test, latency time for withdrawal of the tail was significantly increased with the dose of 55.62 mg/kg at 15 min and 111.24 mg/kg at 30 min. 6. In the tail flick test the antinociceptive effect was dose dependent at 15 and 30 min. 7. From the above results the implication of peripheral and spinal mechanisms in the antinociceptive effect of homotaurine may be concluded.