Background: Thyroid hormones play a vital role in the regulation of metabolism and the proliferation of blood cells. Thyroid dysfunction can lead to various effects on blood cell counts, including anemia, erythrocytosis, leukopenia, thrombocytopenia, and in rare instances, pancytopenia. Additionally, thyroid dysfunction can alter red blood cell indices such as mean corpuscular volume (MCV), mean corpuscular hemoglobin (MCH), mean corpuscular hemoglobin concentration (MCHC), red cell distribution width (RDW) and platelet distribution width(PDW). This study aims to assess the impact of hypothyroidism on blood cell parameters, determining the prevalence and severity of hematological abnormalities in this patient population. Methods: From January 1 to March 31, 2024, a cross-sectional study was conducted at a tertiary care hospital involving 200 patients, out of which 100 were diagnosed with hypothyroidism and 100 were euthyroid selected through systematic random sampling. Hematological data were gathered using data extraction sheets, while information on associated factors was obtained through structured questionnaires and data extraction sheets. Four milliliters of anticoagulated venous blood were collected for complete blood cell count analysis. Data were entered into Epi-data version 3.1 and analyzed using Stata version 14. Both bivariate and multivariate logistic regression analyses were conducted to identify factors linked with hematological abnormalities. A P value of less than 0.05 was considered statistically significant. Results: Analysis of the collected data showed a statistically significant difference between two groups of patients in red blood cell (RBC) count, red cell distribution width (RDW), Mean corpuscular volume(MCV) and Platelet distribution width ( PDW ) (P-value < 0.05). However, there was no significant difference in hemoglobin, mean corpuscular hemoglobin concentration (MCHC), mean corpuscular hemoglobin(MCH), hematocrit (P-value > 0.05). Conclusion: The study revealed a variety of hematological abnormalities in patients with hypothyroidism. Altered RBC count, MCV, hematocrit , RDW and PDW were common findings in patients with hypothyroidism Consequently, early diagnosis and effective monitoring strategies are essential to minimize complications in these individuals.