The inhibition of the corrosion of mild steel in hydrochloric acid solutions by extract of the leaves of Nypa fruticans Wurmb. has been studied using weight loss and hydrogen gas evolution techniques. Inhibition was found to increase with increasing concentration of the leaves extract. A first-order type of mechanism has been deduced from the kinetic treatment of the results and the process of inhibition attributed to physisorption. The inhibition action of N. fruticans was compared with that of 1,5-diphenylcarbazone. The highest inhibition efficiency of 75.11% was observed with N. fruticans and 70.18% for DPC at 30 °C. The results obtained show that the solution extract of the leaves of N. fruticans could serve as an effective inhibitor of the corrosion of mild steel in hydrochloric acid media.