Abstract: In this paper we studied the effect of tuber extract of nutgrass (Cyperus rotundus l.) on fetal weight and length of white rat (Rattus novergicus) Sprague Dawley. Pregnant female rats (n=24) are grouped into four consisted of six rats each. Group-1 (control) only received distilled water. Group-2, 3 and 4 consecutively received tuber extract of nut grass at the dose of 22.5, 45, and 90 mg/kg body weight. Extract was given orally using gavage needle on day 6th for 13 days until day 18th of pregnancy. On day 18th of pregnancy, female rats were lapartomized under deep anaesthesia. All fetuses were taken to measure their body weight and length. The results showed that both fetal weight and fetal length of the rats were significantly decreasing with increasing doses of the extract. In conclusion, tuber extract of nut grass (Cyperus rotundus l.) has inhibitory effects against fetal growth of rats during pregnancy.