The mechanism of inhibition of jack bean and Bacillus pasteurii ureases was investigated by triacontanyl palmitate (1) which is a long-chain fatty ester and has been isolated from Symplocos racemosa Roxb. Lineweaver-Burk, Dixon plots, and their secondary replots showed that 1 is a non-competitive inhibitor of these enzymes. K(i) values were found to be 60.03 +/- 1.72 and 88.23 +/- 0.31 microM against jack bean and B. pasteurii ureases, respectively.