Background: Anemia of pregnancy primarily affects women of low socioeconomic status. Globally, by WHO (World Health Organization) criteria, 52% of pregnant women from undeveloped or developing countries are anemic compared with 20% from industrialized nations. Heterozygous β-thalassemia (βthalassemia trait; β-TT), caused by the inheritance of a single βthalassemia allele, either β 0 or β + , is an important cause of anemia. More importantly, however, its diagnosis is important for the prevention of beta thalassemia major. Objective: To determine the frequency of beta thalassemia trait in pregnant females presenting with microcytic hypochromic anemia in first trimester. Method and Material: This is a cross sectional survey and was conducted in Pathology department, King Edward Medical University, Lahore and all cases were selected from Lady Atchison Hospital and Lady Willingdon Hospital (affiliated with Mayo Hospital, Lahore, Pakistan). After telling the patients about pros and cons of the procedure and taking informed consent and ensuring their confidentiality. The following investigations were carried out from Pathology department, King Edward Medical University, Lahore: Complete blood count: Blood samples were collected in K 3 EDTA vials and analyzed within 1-3 hours of collection by using a haematology analyzer Sysmex KX-21for Hb, total red cell count, MCV and MCH. Peripheral blood smear: Blood films were made from each sample stained by Giemsa and examined for red cell morphology .i.e microcytosis, hypochromia, NRBCs and anisocytosis. Hemoglobin Electrophoresis: Blood samples in K 3 EDTA vials were subjected to cellulose acetate electrophoresis and Hb A 2 estimation done by elution. Results: A total of 120 patients were included. Majority (39%) were between 26 and 30 years of age with a mean and SD 27.43+3.11 years. Mean + SD of the quantitative variables of the patients with beta thalassemia trait were as follows; Hemoglobin 10.77+0.97 g/dL, MCV 62.07+4.26 fL , MCH 19.51+2.45 pg, MCHC was 28.08+2.16 g/dL and mean HbA2 was 4.29+0.37 %. Frequency of beta thalassemia trait in pregnant females presenting with microcytic hypochromic anemia in first trimester was 15.33% (n=19). Conclusion: Beta thalassemia trait is one of the commonest causes of microcytic hypochromic anemia. Pregnant females presenting with microcytic hypochromic anemia should be investigated for beta thalassemia trait along with iron studies. Beta thalassemia trait detection in pregnant females can be an important step for prevention of beta thalassemia major.