Introduction: Thrombocytosis, defined as a platelet count exceeding 450,000/µL, is a common hematological finding with diverse etiologies, including reactive and clonal causes. Platelet indices, such as mean platelet volume (MPV), platelet distribution width (PDW), and plateletcrit (PCT), provide insights into platelet morphology and function, aiding in the differentiation of thrombocytosis subtypes. This study aimed to evaluate the clinicopathological correlation between thrombocytosis and platelet indices in a tertiary care setting. Materials and Methods: A retrospective analysis was conducted on 200 patients with thrombocytosis over two years. Inclusion criteria included patients aged >18 years with persistent thrombocytosis, while exclusion criteria encompassed those with recent trauma, surgery, or pregnancy. Data on demographic details, clinical presentation, etiology, and platelet indices were collected and analyzed. Results: Of the 200 patients, 65% had reactive thrombocytosis, while 35% had clonal thrombocytosis. Platelet indices such as MPV and PDW were significantly higher in clonal thrombocytosis compared to reactive cases (p<0.05). Five tables were constructed to summarize the findings, including demographic distribution, etiological classification, and platelet index correlations. Conclusion: Platelet indices, particularly MPV and PDW, are valuable tools in differentiating reactive from clonal thrombocytosis. This study highlights their potential utility in clinical practice for early diagnosis and management.