Abstract: In a country like India where most women present late in third trimester and may not keep menstrual record properly, a method was needed which can help to estimate gestational age in third trimester. So this study was done on 100 pregnant women ranging from 28 to 42 weeks of gestation, attending the OPD of SIMS,Hyderabad, A.P, India, during the period July 2009 to Sep 2010. Patients with high risk factors affecting the growth of baby were excluded from the study. These women were subjected to single exposure of ultrasonography estimation of gestational age using multiple foetal parameters like BPD, FL, HC.