Several therapeutic effects including diuretic, anti-pyretic and anti-scurvy have been - reported for Portulaca oleracea. In previous studies the analgesic, anti-inflammatory, antihypertensive, anti-oxidant, muscle relaxant effects and neuropharmacological effects of the, aqueous extract of Portulaca oleraceal1ave been demonstrated on experimental animals. In the present study the antitussive effect of this plant was evaluated. The antitusive effects of aerosols of two different concentrations of boiled extract, codeine: and saline were tested by. , counting the number of coughs induced by citric acid aerosol 10 min following exposure of animals. The effective concentration of extract causing 50% reduction of cough number (EC50) was also determined. The results showed "significant reduction (p<0.001) in cough numbers following the use of both concentrations of the boiled extract (10.7 0.16 and 6.7 0.33 for %2.5 and %5 extracts respectively) compared to saline (14.8 0.30). In addition there was a significant difference (p<0.01) between the cough numbers of the 5% extract with that of codeine (10.2 0.38). In this study, EC50 of the plant extract was 4.5%. These results showed that the antitussive effect of Portulaca oleracea L. was comparable to codeine.