Aims: Thyroid hormones have been shown to influence the immune system and haematopoiesis. The aim of this study was to evaluate some immunological and hematological parameters in peripheral blood of hypo-or hyperthyroid women. Materials and Methods: Blood samples were collected from 50 women with hypothyroid disease, 50 women with hyperthyroid disease and a control group consisting of 50 sex -and age -matched euthyroid subjects. Thyroid function assesed according to measurent of T3, T4 and TSH levels. The complete blood count (CBC), total and differential counts of white blood cells (WBC), serum levels of immunoglobulins (IgG, IgA, IgM and IgE) and C3 and C4 complement components determined in three groups by using standard immunological and hematological methods. Results: In hyperthyroid women the mean serum concentrations of IgG (2312.4±584 mg/dl), IgA (296± 87 mg/dl) and IgE ( 301± 264 IU/ml) were significantly higher than those found in the control group (1539± 974 mg/dl, P<0.0003; 234± 116 mg/dl, P<0.01; 109.8±115 IU/ml, P<0.0001, respectively) and the mean MCV was significantly lower in comparison with the euthyroid group (P<0.05). Hypothyroid patients had higher serum IgE concentrations in comparison with the euthyroid group (179.8± 218 IU/ml vs. 109.8± 115 IU/ml; P<0.047). The mean serum C3 concentration in hypothyroid patients was also significantly higher in comparison with the euthyroid group (138.7± 36.6 mg/ml vs. 117.8± 32.1 mg/dl; P<0.01). In the hypothyroid group the mean eosinophil count was markedly higher in comparison with the hyperthyroid group (P<0.06) and the mean count of RBC and the levels of some RBC-related indices, such as hematocrit and hemoglobin, were significantly lower in comparison with the euthyroid group (P<0.05). Conclusion:These results indicate hypergammablobulinemia and lower MVC in hyperythyroid patients, and higher IgE levels, C3 levels and eosinophil count as well as anemia in hypothyroid patients.