INTRODUCTIONHypothyroidism is a common disease with varying frequency between countries. A decreased thyroid hormone adversely affects erythropoiesis; anemia develops in hypothyroidism. 1 Abnormalities in hematological parameters have been noted in patients with thyroid diseases. Nevertheless, the exact mechanism of thyroid hormones action on human hematopoiesis is exactly not clear.2 According to the data of WHO, anemia prevalence is 24.8% throughout the world and it is seen more frequently in underdeveloped countries. 3Prevalence of anemia in subclinical and overt hypothyroid groups was 26.6 % and 73.2 %, respectively. Thus, the frequency of anemia in subclinical hypothyroidism is higher than in general population (nonhypothyroid). Therefore, presence of hypothyroidism is a risk factor for anemia. Normocytic anemia, which is the most frequent type of anemia in hypothyroid patients is caused by lack of stimulation of erythroid colony development, reduction in oxygen distribution to tissues and diminution of erythropoietin level. 4 The second most common type of anemia is microcytic anemia due to iron deficiency (43.2%) which is one of the most frequently ABSTRACT Background: The association between anemia and hypothyroidism has been recognized, although the prevalence of anemia in hypothyroid patients varies widely between studies. The main objectives were to study the prevalence, type, etiology of anemia in primary hypothyroidism and to correlate severity of anemia with severity of hypothyroidism. Methods: A case control study was carried out in a tertiary care hospital. Newly diagnosed 60 overt primary hypothyroid patients and 180 euthyroid controls were evaluated for anemia. Morphological types of anemia, their etiology were studied. Severity of anemia was correlated with that of hypothyroidism. Results: Anemia was observed in 45 patients with hypothyroidism. Symptoms due to anemia were significantly higher in cases than in the anemic controls. RBC morphology showed normocytic normochromic in 39, microcytic hypochromic in 14 and macrocytic in 7 cases. Serum iron was significantly lower in the cases than in the controls. Serum anti-TPO positivity was 63.33% in cases as compared to 10% in controls. Anemia was severe in cases with high TSH. Conclusions: The prevalence of anemia was 75% which was higher than that seen in the euthyroid controls. Hypothyroid patients were more symptomatic for anemia than the controls. Normocytic normochromic type of anemia was the most common type in our study. Autoimmunity in the form of anti-TPO positivity was detected in 69% of anemic cases. Iron deficiency was observed in the cases more than in the controls. There was a statistically significant negative correlation between TSH and hemoglobin.