Thrombocytopenia is a relative decrease of platelets in blood. Thrombocytopenia is defined as platelet count less than 150000 per micro liter. A normal human platelet count ranges from 150000 to 450000 per micro liter of blood. Thrombocytopenia results from one or more of three processes: (1) decreased bone marrow production; (2) sequestration, usually in an enlarged spleen; and/or (3) increased platelet destruction. Disorders of production may be either inherited or acquired. Common causes of thrombocytopenia are infections, drugs, autoimmune, Hypersplenism, DIC, etc. We analyze 300 cases (age >12 years) of thrombocytopenia (platelet count < 1.5 lacs) between June 2015 to November 2018 in department of medicine, department of pediatrics at Maa UMA Multi–specialty Hospital Unjha, North Gujarat, India. Infections, ITP, hypersplenism, DIC and drugs are the common causes of thrombocytopenia. Patechie, purpura and gum bleeding are the most common bleeding manifestation. Bleeding symptoms more common with platelet count <20000. P.Vivax malaria is associated with severe thrombocytopenia and bleeding manifestations. Dengue patients may have prolonged bleeding time and bleeding symptoms even with mild to moderate thrombocytopenia suggestive of functional platelet defect.