The present study deals with evaluation of the anti-inflammatory and analgesic properties of a lyophilized leaf extract of Argemone mexicana Linn. on laboratory animal. The anti-inflammatory study was done by using carrageenan-induced paw edema method. It was found that lyophilized extract can be effective in acute inflammatory disorders and in that case, it showed significant anti-inflammatory dose-dependent effect (p<0,001) at the dose level of 250 mg/kg and 500 mg/kg. The plant extract was equally tested for its analgesic potential by using the hot plate test method and acetic acid Writhing method. The lyophilized extract was found to exhibit significant (p<0,01; p<0,001) analgesic activity in tested model. By the hot plate method, the drug extract showed significant (p<0,001) increased latency period than the control group at oral dose of 250 and 500 mg/kg. In acetic acid induced writhing test, the lyophilized extract (250 & 500mg/kg) presented reduced number of writhes at the two dose levels, which were found significant (p<0,05; p<0,001) if compared to control group. These results support the use of Argemone mexicana Linn. for the treatment of pain and inflammation sickness.