Objectives: To identify anthracycline induced acute (within one month) and early onset chronic progressive (within year) cardiotoxicity in children younger than 16 years of age with childhood malignancies at tertiary care center of Pakistan. Design: Prospective Cohort study. Setting: Aga Khan University, Karachi, Pakistan. Participants: 110 children (aged 1 month to 16 years). Intervention: Anthracycline (Doxorubicin and/or Daunorubicin). Outcome measurements: All children who received anthracycline as chemotherapy and three echocardiographic evaluations (baseline, one month and 1 year) between July 2010 and June 2012 were prospectively analyzed for cardiac dysfunction. Statistical analysis including systolic and diastolic functions at baseline, 1 month and 1 year were made by repeated measures analysis of variance (r-ANOVA). Results: Mean age was 74±44 months and 75 (68.2%) were males. Acute lymphoblastic leukemia (ALL) was seen in 70 (64%) patients. Doxorubicin alone was used in 59 (54%) and combination therapy was used in 35(32%). A cumulative dose of anthracycline <300mg/m2 was in 95 (86%). Fifteen (14%) children developed cardiac dysfunction within a month and 28(25%) children within a year. Of these 10/15 (66.6%) and 12/28 (42%) had isolated diastolic dysfunction respectively, while 5/15 (33.3%) and 16/28 (57%) had combined systolic and diastolic dysfunction. Seven (6.4%) patients expired due to severe cardiac dysfunction. 8/59 (13.5%) children receiving doxorubicin showed dysfunction mostly related to higher cumulative dose (p=<0.001). Cardiotoxicity was high where combination of doxorubicin and daunorubicin was used (p=0.004). Conclusion: Anthracycline induced cardiac dysfunction is high. Long term follow-up is essential in children received any dosage of anthracyclines because of its late manifestation.