Purpose: The purpose of the study is to evaluate the analgesic and anti-inflammatory activity of new synthetic compound: 5-amino-3-phenyl-1,3,5-thiadiazine-2-thione and to compare its effects with the available standard drug, diclofenac sodium in mice. Methods: This test compound was evaluated for its anti-nociceptive activity using hot plate and writhing models, while for antiinflammatory activity evaluation, carrageenan and histamine-induced paw edema models were used. Results: In hotplate test, the latency time (in seconds), at 90 minutes of the administered doses (60 and 120 mg/kg) of 5-amino-3- phenyl -1.3.5-thiadiazine-2-thione were 19.5 seconds (p < 0.05) (Mean latency time) and 21.5 seconds (p < 0.01) (Mean latency time) respectively. In writhing test maximum inhibitory effect was demonstrated at a dose of 120 mg/kg with an average of 1.4 (p < 0.001) wriths (this inhibition was more significant) followed by 60 mg/kg (Mean number of wriths = 1.6) (p < 0.001) . The anti-inflammatory effect of the compound for 60 and 120 mg/kg doses was found to be significant and was more significant for 120 mg/kg in both histamine and carrageenan-induced paw edema models. Conclusion: It has been concluded that 5-amino-3-phenyl-1,3,5-thiadiazine-2-thione represents, dose-dependent antinociceptive and anti-inflammatory properties, which are statistically significant. The test compound showed a significant in-vivo peripheral analgesic effect in the writhing test, in comparison to the diclofenac sodium.