A series of newer substituted-imidazolidine derivatives 3a-k were synthesized and assayed in vivo to investigate their anti-inflammatory, analgesic and antiulcer activity. The results of biological evaluation revealed that the three compounds, 4-[1,3-bis(4-hydroxy-3-methoxybenzyl)-2-imidazolidinyl]phenyldiethylamine (3g), 4-[1,3-bis(3-Ethoxy-4-hydroxybenzyl)-2-imidazolidinyl] phenyldiethylamine (3h) and 4-(1,3-bis(benzo[d][1,3]dioxol-5-ylmethyl)-4-methylimidazolidin-2-yl)-N,N-diethylbenzenamine (3j) were good in their anti-inflammatory and analgesic actions. Additionally these derivatives showed superior GI safety profile as compared to that of the standard drug in terms of low severity index. The results are statistically treated for its significance.