Crude ethanolic extract of Lawsonia inermis L. (0.25-2.0 g/kg) produced significant and dose-dependent anti-inflammatory, analgesic, and antipyretic effects in rats. The extract also produced significant increases in pentobarbitone-induced sleeping time. Using a liquid-liquid extraction procedure, the extract was fractionated into chloroform, butanol, and water fractions, and these were tested for the above activities. The butanol and chloroform fractions showed more potent anti-inflammatory, analgesic, and antipyretic effects than the crude extracts, while the aqueous extract showed significantly less effect. As compared with the other extracts, the butanolic extract (500 mg/kg) was the most effective in the analgesic test. From the chloroform extract, a pure compound was isolated and identified, using chromatographic and spectroscopic techniques, as 2-hydroxy-1,4-naphthaquinone (lawsone). The isolated compound was found to possess significant anti-inflammatory, analgesic, and antipyretic activity. It potentiated significantly the pentobarbitone-induced sleeping time. The anti-inflammatory effect of lawsone (500 mg/kg) was not significantly different from that of the reference drug phenylbutazone (100 mg/kg).