Septicemia is a common cause of high neonatal mortality. It is caused by organisms invading the blood stream, which may be caused by bacterial, viral, fungal and protozoal infections. Septicemia is characterized by positive blood culture, neutrophilia, thrombocytopenia, elevated C-reactive protein and increased erythrocyte sedimentation rate. Septic shock is the most dangerous complication of septicemia. Thrombocytopenia is considered when platelet count falls below 150×109/ L. Endotoxins or platelet activating factor may cause abnormal bleeding. After 72 hrs of birth, thrombocytopenia may be severe and prolonged. Thrombocytopenia is caused by disseminated intravascular coagulation. Platelet indices studied are meanplatelet volume, platelet distribution width and plateletcrit. Hence the present study is being undertaken to evaluate thrombocytopenia and variations in platelet indices in neonatal sepsis. The Present study was planned in Department of Pediatrics, Darbhanga Medical College & Hospital, Laheriasarai, Bihar. The 100 cases of the neonatal sepsis were enrolled in the present study. The cases were divided in two study groups. The Group A consist of 50 patients of sepsis cases. The remaining 50 cases were enrolled in Group B as control without sepsis. Smears are made from peripheral blood and stained by Leishmans stain and examined to confirm thrombocytopenia. Platelet indices collected from automated machine Sysmex XT-2000i and Sysmex XE -2100.Bacterial and fungal organism type is detected by Blood culture and Gram staining. (From microbiology department). The data generated from the present study concludes that Thrombocytopenia was the most sensitive marker for culture-positive sepsis. The platelet count decreased with development of sepsis and PDW and MPV increased in septic babies. Platelet indices did not differ significantly with gestational age or with Gram‑positive or Gram-negative blood culture. This study is useful for evaluating platelets indices as a marker of neonatal sepsis alone or with combination to pre-existing sepsis screen.