We prospectively compared gender outcome among 470 MMT patients admitted between June 1993 and Dec 2002. Urine samples were analyzed for drug abuse after one month and after one year. On admission females 131(27.9%) were significantly younger (34.5 +/-7.5 years) than males 339(72.1%) (37.3 +/- 8.3 years) (ANOVA; F = 11, p = 0.001) and had significantly higher cocaine abuse (20% vs. 11.3%) (Fisher's Exact Test, p = 0.02). After one year, groups had: (a) similar retention in treatment (76.3%-females, 72.6%-males), (b) stop in opiate abuse (65%-females, 65.3%-males), (c) a net decrease in cocaine abuse (% positive that became negative minus % negative that became positive) (68.0%-females, 51.6%-males). Females who were admitted to treatment while pregnant (n = 45) were significantly younger (31.5 +/-5.4 years) compared to 86 non-pregnant (36.1 +/- 7.9, ANOVA F = 12.1, p = 0.001). We concluded that compared to males, females started MMT younger and had a higher proportion of cocaine abuse even though females' outcome were similar to males'.