The normal physiological changes during pregnancy, the iodine adequacy, medication and presence of goitrogens in different geographical region altogether dictates the thyroid status in the body. (1-5) Topography, nutrition intake, socioeconomic status and cultural practices also contribute significantly. Indian thyroid society has taken recommendation of American thyroid association strongly recommends population defined , trimester-wise and region specific reference range for the diagnosis(6,7) Aim and Objectives To evaluate the thyroid hormone in different trimester of normal pregnancy. Material And Method Total of 150 normal pregnant women (50 in each trimester ) enrolled for study. Their FT3,FT4 and TSH were estimated. Observation And Result Range of FT3 is 1.76-4.08 pg/ml in first trimester, 1.54-4.83 pg/ ml in second trimester and 1.24 4.91 pg/ml in third trimester. Range of FT4 is 0.74-4.03ng/dl in the first trimester, 0.70-3.86 ng/dl in second trimester and 0.60-4.67 ng/dl in third trimester. Range of TSH in the first, second and third trimesters were 0.46-5.72mIU/ml, 0.60-5.10 mIU/ml, 0.39-6.68mIU/ml, respectively. Conclusion Free T3 and FreeT4 level increases subsequently from first to third trimester and TSH level decreases from first to third trimester