Objective: To analyze the case series of malignant ovarian tumor in adolescents (13–21 years) with various presentations, histopathological types and management. Design: Case series. Settings: Department of Obstetrics and Gynaecology, Sri Ramachandra Medical College and Research Institute (SRMC), Chennai, Tamil Nadu, India. Period: January 2015 to January 2016. Materials and methods: Adolescent female patients with malignant ovarian tumor were included. Clinical history, examination findings, radiological findings, surgical management, histopathology types were analyzed. Results: During the study period of 1 year, 10 girls with malignant ovarian tumors were studied. Majority of patients were 19–21 years of age. The main presenting complaints were pain abdomen in 50% of patients, followed by abdominal distension in 30% and menstrual irregularities in 20%. Of the 10 cases, 8 were of non-epithelial origin and 2 were epithelial. Fertility-conserving treatment was performed in all patients but for a single patient with endodermal sinus tumor (EST). Conclusion: Though benign ovarian lesions are very common, malignant ovarian tumor represent 1.5% of all tumors in adolescents. Clinical examination, radiological and biochemical tests together help us in arriving at an accurate diagnosis. The main attention is towards the timely diagnosis and fertility-conserving procedures in these young patients.