Context: Oligohydramnios is a dangerous condition for health of the fetus and is linked to higher foetal morbidity. If the proper steps are not done in a timely manner, this condition frequently raises the chance of various outcomes. Early oligohydramnios identification and therapy may contribute to a drop in caesarean births and a reduction in perinatal morbidity and death. Aim: Evaluate oral hydration therapy for improving AFI in cases of antenatal mothers with oligohydramnios. Methods: A pre-experimental research design (one group pre and post intervention) was carried out 36 antenatal mother with singleton pregnancy and gestational age between 32-34 weeks with oligohydramnios (AFI≤6) were selected based on non- probability convenience sampling technique. Data collection was performed based on the interview schedule. The study subjects were asked to drink 1500ml of water per day orally for seven days apart from their daily fluid intake. AFI measurement was carried out on day zero and day seven. Results: Majority of the mothers has severe level of oligohydramnios (69.4%) in pre - intervention. After the oral hydration therapy mothers has normal (50%), mild (19.4%) and moderate (30.6%) level of oligohydramnios. The pre intervention mean: 5, SD =0.793 and post intervention mean: 7.53, SD =1.54. It was highly significant at p<0.000. Conclusion: The oral hydration therapy was more effective to improving the level of Amniotic Fluid Index among antenatal mothers with oligohydramnios. It was a simple and safe measure with nil adverse effects for mother and fetus.