Aim: The study was conducted with the aim of evaluating the placental thickness, as a parameter for estimating gestational age of the fetus. Materials & Methods : This study consists of 100 pregnant females, between 13th to 39th weeks gestation with their age ranging from 18 -35 years, attending antenatal clinic at the department of Obstetrics and gynecology, Pt.J.N.M. Medical College & Dr. B.R. Ambedkar Memorial Hospital Raipur (C.G.) from October 2008 to august 2009. USG was done by using Gray scale real time( LOGIQ 400) machine employing a 3.5 MHz convex transducer. After estimating the fetal age by BPD, HC, AC, and FL the placental thickness (PT) was measured perpendicular to the basal and chorionic plates, in the mid portion of the placenta at the level of insertion of umbilical cord. esults: It was observed that the placental thickness gradually increased from 16 mm at 15 weeks of gestation to 37 mm at 39 weeks. From 23rdweek to the 34th of gestation the placental thickness coincide almost exactly with the gestational age in weeks. Conclusion: To conclude, the measurement of the placental thickness is an important parameter for estimation of fetal age along with other parameters especially in the late mid trimester and early third trimester, where the exact duration of pregnancy is not known.