In addition to being a widely consumed vegetable in West Africa, the leaves extract of Telfairia occidentalis is believed to have beneficial health effects and is used in tradomedical preparations. The effect of saline extract of T. occidentalis leaves on sickle and normal erythrocytes membrane stability was investigated. Human erythrocytes exposed to hypotonic and heat stress, by incubation in a buffered hypotonic medium at 56 degrees C, were stabilized by the extract in a doze dependent manner. The maximum stability was 72.3 +/- 3.1% and 55.0 +/- 4.1% for the sickle and normal erythrocytes membrane respectively (p < 0.0001). This study indicates that T. occidentalis has human erythrocyte membrane stabilizing activity. In addition the marked difference in the observed effect between the normal and sickle erythrocytes membranes suggests that pharmacogenetic factors may be involved in the response to herbal preparations.