The ethyl acetate extract of the stem bark of Pouteria campechiana afforded 3b, 28-dihydroxy-olean-12-enyl fatty acid ester 1, a mixture of a fatty acid ester of oleanolic acid 2a and a fatty acid ester of betulinic acid 2b in a 0.3:1 ratio, and spinasterol 3 by silica gel chromatography. The structures of 1-2b were elucidated by extensive 1D and 2D NMR spectroscopy. The structure of 3 was identified by comparison of its 1H NMR data with spinasterol. Antimicrobial tests on 1 and a mixture of 2a and 2b indicated that they are slightly active against the bacteria, Escherichia coli and Pseudomonas areruginosa and the fungi, Candida albicans and Trichophyton mentagrophytes. They are inactive against Staphylococcus aureus, Bacillus subtilis, and Aspergillus niger.