This book discussed on etiology of thrombocytopenia whether it occur due to microbial infections such as Malaria or Kala-azar or due to infection with pathogenic or opportunistic bacteria and also studied others non microbial causes of thrombocytopenia whether its due to congenital defect or associate with pregnancy. In this book we try to give clear picture about thrombocytopenia to enable every medical students to understands this real disaster in order to prevent and treat it accurately.