Abstract : Juvenile myelomonocytic leukemia (JMML) is a rare blood cancer occurs in young children characterized by proliferation of myelomonocytic cell and to which no recurrent chromosomal rearrangement has been associated. Here we report a 3-year old boydiagnosed as Acute Myelomonocytic Leukaemia (AMML), who actually transformed from JMML. JMML could have been suspected earlier when he presented as monocytosis and mild splenomegaly. At that time patient was treated as infection and regular follow-up showed persistent monocytosis. After 2 years of follow-up, patient had full blown blastic in transformation. Further investigation showed consistent with AMML. Cytogenetic analysis revealed 46 XY del (6p), -22. Patient received standard induction chemotherapy for acute myeloid leukaemia but achieving remission only after the fourth course of re-induction. Our case highlights Acute Myelomonocytic Leukemia with rapid blastic transformation from JMML and the challenges in managingpatient with AML cytotoxic chemotherapy. The underlying 46XY, del (6p) could possibly be the factors for rapid blastic transformation and resistant to cytotoxic chemotherapy