Aims: Solanum trilobatum Linn., (Solanaceae) is one of the most widely used plants as food supplement in southern part of India and some parts of Southeast Asia. This plant is traditionally used for the treatment of respiratory illness. In animal studies, the extract of S. trilobatum showed significant antimicrobial, hepatoprotective and anticancer activities. The complete phytochemical profile, antimicrobial and mast cell stabilizing activities of S. trilobatum remains unclear. This study tests the antimicrobial, antihistaminic and mast cell stabilizing activities of ethanolic extract of leaves of S. trilobatum (EEST). Methodology and results: The phytochemical test was carried out using chemical and instrumental [Gas Chromatography Mass Spectrometry (GC-MS)] analytical methods. Antimicrobial effect of EEST was tested against Streptococcus pneumonia, Escherichia coli and Staphylococcus aureus. Intestinal mesentery of Sprague Dawley (SD) rats was used to study the peritoneal mast cell stabilization activity of EEST. The rat intestinal mesentery was exposed to 50, 100, 200, 300, 400 and 600 μg/mL of EEST and the peritoneal mast cell stabilization activity was compared with that of standards (pheniramine 20 μg/mL and ketotifen 20 μg/mL). The phytochemical test showed the presence of carbohydrates, saponins, flavonoids, alkaloids, tannins and phenolic compounds. GC-MS analysis indicated the presence of 45 fragmented compounds which included epoxylinalol, himachalol, illudol, epibuphanamine, baimuxinal and edulan IV. EEST exhibited antimicrobial activity at 10 mg/mL against S. aureus, S. pneumonia. Significant mast cell stabilizing activity was observed from the dose of 100 μg/mL to 600 μg/mL. Conclusion: Ethanolic extract of leaves of S. trilobatum possess significant antimicrobial and antihistaminic activity.