['To evaluate the antinociceptive activity of acute and chronic administration of petroleum ether extract of Murraya koenigii L. leaves (PMK) and total alkaloids separated from petroleum ether extract of Murraya koenigii leaves (AMK) in mice.', "PMK was subjected for isolation of total alkaloid fraction AMK. The antinociceptive activity of PMK (100 and 300 mg/kg, p.o.) and AMK (100 and 300 mg/kg, p.o.), after acute and chronic administration (for 15 days), was evaluated using peripheral model like acetic acid-induced writhing method and central model like hot plate method and tail immersion method. Statistical analysis was carried out by one-way ANOVA followed by Dunnett's test.", 'In acute studies, PMK and AMK significantly and dose-dependently reduced the number of acetic acid-induced writhing, significantly increased the latency of paw licking in hot plate method, and significantly increased the basal reaction time in tail immersion method. With chronic administration of PMK and AMK, highest activity was observed on day 9 in acetic acid-induced writhing model. In hot plate and tail immersion method, chronic administration of PMK and AMK initially showed fluctuating responses but produced highest degree of antinociception on day 9 of the study.'] Does antinociceptive activity of acute and chronic administration of Murraya koenigii L. leave in experimental animal models?