Pancytopenia is a very common entity among children in today’s scenario. The cause of pancytopenia can be varied from drug induced bone marrow depression to leukaemia. So, the objective of this study is to determine the cause of pancytopenia among children by haematological parameters (complete blood count) and bone marrow aspiration in a tertiary health care centre. Material and method- A retrospective study was done patients below 18 years of age, diagnosed with pancytopenia at Patna Medical College and Hospital between May2010 to October 2012. Result-258 children were found to have suffered from pancytopenia during the study period. Age ranged from 4 and ½ months to 18 years. Out of 258 cases 62.4% were male and 37.6% were female. Generalised weakness and pallor were the most common clinical presentation of pancytopenia in children. Haematological parameter and bone marrow aspiration was diagnostic. Megaloblastic anaemia followed by hypoplastic anaemia were the most common forms.