In this study, the pharmacologic effects of Solanum lycopersicum leaves extract were investigated by observing the Nitric Oxide (NO) production. The inflammatory activity of LPS-stimulated murine macrophage cells RAW264.7 treated with different concentration of tomato leaves extract (0, 20, 50 and 100g/ml) were monitored by Griess assay. Results showed that the tomato leaves extract inhibited the productions of NO which plays a central role in the anti-inflammatory response. At the highest concentration (100g/ml) of the tomato leaves extract tested, the NO production was inhibited by 84.95%. The results were further investigated by observing the Prostaglandin E2 (PGE2) level. The results agreed with the previous observation when at the highest concentration (100g/ml) of tomato leaves extract tested, the PGE2 production was reduced by 37.41% compared to the untreated, indicating anti-inflammatory activity.