Context: Platelet count estimation is an essential element of routine hemogram. It is crucial in the management of hemorrhagic disorders. Manual platelet count correlation using a peripheral smear or Neubauer chamber is one of the methods used when automated platelet counts are found to be abnormal (especially in cases of severe thrombocytopenia). It is neither practicable nor economical to routinely corroborate abnormal platelet values by immunological platelet estimation (flowcytometric analysis using antibodies against platelet cell surface antigens such as CD41, CD42, CD61)¹. Hence, manual platelet count estimation remains a more feasible alternative for review of low machine counts across laboratories around the world. Aim: We sought to comparatively analyze the platelet estimation derived from manual modality with respect to that derived from automated haematology analyzer. Methods: This prospective cross sectional study included both in-patients and out-patients who were admitted in or presented to Meenakshi Medical College Hospital & Reserch Institute (MMCHRI), Kanchipuram, Tamil Nadu between Mar 2024 and May 2024. Blood samples were retrieved from 500 patients of both paediatric and adult age groups and either gender. Samples were collected in EDTA vacutainers and peripheral smears were prepared from the same using Leishman's stain. Platelet enumeration was done both by automated and manual slide method and the results compared. Conclusion: We noted an excellent correlation between the platelet counts obtained by traditional slide method and automated cell counter method at normal ranges of platelet values. However, at markedly high (Platelet count ≥ 700×10³/μL) and low counts (Platelet count ≤ 20x10³/μL) and in cases with high mean platelet volume (MPV >14 fL), relatively poor correlation between both the methods was noted. Hence, this study underscores the importance of manual verification of platelet counts in thrombocytopenic patients, especially those with values close to the threshold for prophylactic platelet transfusion (≤20×10³/μL).