Background:Subclinical maternal thyroid dysfunction adversely affects the obstetrical outcome. Treatment of subclinical hyper or hypothyroidism clearly improves the pregnancy outcome. Therefore screening of thyroid function in pregnancy is the need of time. Objective: To determine the frequency of subclinical thyroid dysfunction among pregnant women with bad obstetrical history Design:Cross sectional study. Sampling technique:Non-probability convenient sampling. Materials and methods:This study was done at Chohan Reproduction and Assisted Fertility Treatment Center (CRAFT-IVF) in duration of 2 year. 260 pregnant women of age 18-40 years with bad obstetrical history were enrolled. Informed consent was obtained and demographic history like, age, gestational age, obstetrical details were taken. Blood samples were taken for thyroid hormones i.e. fT3, fT4, and TSH levels in first antenatal visit in outpatient department. Interpretation of thyroid dysfunction was done. Data analysis was done on SPSS version 16.0.Mean and standard deviation calculated for fT4, fT3 and TSH. Frequency and percentages were calculated for subclinical thyroid dysfunction. Results:260 pregnant females were enrolled in study to evaluate subclinical thyroid dysfunction. Mean age of the patients was 30.31 + 3.11. Mean fT4 level was 1.84 ±1.12ng/dl, fT3 2.62 + 1.14ng/dl and TSH level was 4.32 ± 0.91mIU/l. Thyroid dysfunction was observed in 118 (45.4%). Out of which subclinical hypothyroidism was noted in 77 (65.2%) pregnant whereas subclinical hyperthyroidism in 41 (34.7%) of patients with bad obstetrical history. Conclusion:Frequency of subclinical thyroid dysfunction is high in our population so it should be considered and managed in pregnant women especially with bad obstetrical history.