Introduction: Ovarian cyst is the sac-like formation filled with brownish fluid and sebum in the ovarium. Most ovarian cysts are benign, and the potential to develop malignancy is only 2%. The malignant cyst is considered as cancer type. This study aimed to analyze the prevalence and associated factors of ovarian cyst malignancy. Methods: This crossectional based study used 84 samples of women with an ovarian cyst in Surabaya. The detection of ovarian cyst is conducted by ultrasound and histopathological examination to determine the level of malignancy. Results: From 84 cases, there were 3 cases of ovarian cyst malignancy (3.6%). There was a significant difference in the level of malignancy based on age (p= 0.000). The ovarian cyst in patients over 50 years old was more likely to develop into a malignant cyst. The majority of ovarian cysts subtype were bilateral cyst and endometriosis cysts, consist of 31 patients (36.9%) and 22 patient (26.2%) respectively. Analysis for the cyst location, majority of ovarian cysts was located bilaterally consist of 47 patients (56.0%). All patients with malignant cyst were not experience bleeding. There were no significant differences on category of cyst (p= 0,674), location of cyst (p= 0.294) and the presence of bleeding (p= 0.541). Conclusion: The prevalence rate of ovarian cyst malignancy was 3.6% with age as a significantly associated factor.