Background: Early detection of the nature of the tumor is crucial for the management of patients with ovarian tumor. The type of an ovarian tumor can be determined using serum markers, color doppler USG, and a CT scan. These assist clinicians in diagnosing and managing patients with ovarian tumors, as well as establishing treatment plans. Objective: To compare the accuracy of color doppler ultrasound with CT scan for detection of malignant ovarian tumor. Materials and Methods: It was a cross sectional analytical study that conducted in the Department of Gynecological Oncology, Bangabandhu Sheikh Mujib Medical University (BSMMU) and National Institution of Cancer Research & Hospital (NICRH), Dhaka. Total 65 consecutive patients attending at the inpatient department of BSMMU and NICRH with ovarian tumor were enrolled for the study. All the patients were selected by clinically, ultrasonography findings and serum marker (CA 125, CA 199, CEA, Alfa fetoprotein and LDH) study. For all these patients color doppler USG and CT scan were done. Patients then undergo laparotomy with frozen section biopsy and taking the histopathology report as a gold slandered. Level of significance was assumed at p value <0.05. Results: The sensitivity of Color Doppler USG and CT scan are 96.9% and 87.5%, respectively. The specificity of Color Doppler USG and CT scan are 60.6% and 57.6%, respectively and the accuracy of Color Doppler USG and CT scan are 78.5% and 72.3%, respectively. The positive predictive values of Color Doppler USG and CT scan are 70.5% and 66.7%, respectively. The negative predictive values of Color Doppler USG and CT scan are 95.2% and 82.6%, respectively. Conclusion: The results of the Color Doppler USG are compared to those of the CT scan results. Results found that the diagnostic accuracy of color doppler ultrasound and CT scan are almost similar for detection of ovarian tumor whether it is benign or malignant.