Ent-kaurenoic acid (1), isolated from the dichloromethane extract of Smallanthus sonchifolius leaves, was screened for its antibacterial activity against Staphylococcus aureus, Staphylococcus epidermidis, Bacillus subtilis, Escherichia coli, Enterobacter aerogenes, Klebsiella pneumoniae, and Pseudomonas aeruginosa, and for its antifungal activity against Candida albicans, Trichophyton rubrum, and Epidermophyton floccosum. With the disk diffusion method, 1 was found active against all the Gram-positive organisms tested (S. aureus, S. epidermidis, B. subtilis) at the lowest concentration of 1,000?g/ml while at 10,000?g/ml, 1 was active against the fungus, T. rubrum. No inhibitory activity was observed against C. albicans, E. floccosum, and all the Gram-negative test strains. The Activity Indices (AI) of 1 were noted to be highest against S. aureus, and lowest against T. rubrum. Statistically significant differences were found between the mean Inhibition Zones (IZ) of 1 and the standard drugs (ofloxacin and clotrimazole). The results of the broth dilution Minimum Inhibitory Concentration (MIC) determination revealed that 1 exhibited moderate activity against S. aureus and S. epidermidis, with MIC values of 125?g/ml and 250?g/ml, respectively; and weak activity against B. subtilis, with a MIC value of 1,000?g/ml. The growth of T. rubrum, on MIC assay, was not inhibited at the highest tested concentration of 1 (10,000?g/ml). The Minimum Bactericidal Concentration (MBC) values indicated that the bactericidal activities of 1 occurred at concentrations higher than its growth inhibitory concentrations. Furthermore, the MBC:MIC ratio of 2:1 clearly demonstrated the in-vitro bactericidal effect of 1 against S. aureus and S. epidermidis.