Objectives In the literature, the epidemiological pattern of ovarian neoplasms in different age groups in the Almadinah Almunawwarah region in KSA has not been completely elucidated. Moreover, an unusually frequent diagnosis of adult granulosa cell tumour (AGCT) has been observed in patients in Almadinah Almunawwarah, KSA. This study aimed to describe the pattern of ovarian neoplasms in different age groups in the Almadinah Almunawwarah region with particular emphasis on AGCT. Methods Histopathological records of all ovarian specimens diagnosed from 2011 January to 2016 December were collected from the Maternity and Children Hospital in Almaadinah Almunawwarah, KSA. Hematoxylin and eosin (HE)-stained microscopic slides of serous and mucinous epithelial borderline neoplasms and of malignant epithelial, sex cord-stromal and germ line neoplasms were identified and examined. The tissue sections from the AGCT were stained immunohistochemically with BRCA-1 antibody. Results A total of 301 ovarian specimens were obtained. Of the specimens, 217 (72%) were neoplastic and 84 (28%) were non-neoplastic. In total, 135 (63%) of the neoplastic specimens were benign, 16 (7%) were borderline tumours, and 66 (30%) were malignant tumours. Moreover, 41 (62%) of the malignant tumours were surface epithelial carcinomas, 17 (26%) were sex cord-stromal tumours, and 8 (12%) were germ cell tumours. The incidence of AGCT was unusually high, which accounts for 26% (16/66) of all malignant ovarian neoplasms. Altered BRCA-1 expression was observed in only two specimens. Conclusion In this study, malignant ovarian neoplasms accounted for 30% of all neoplastic ovarian specimens, and the incidence of AGCT was remarkable. Such tumours did not show a significantly altered expression of BRCA-1. Further studies must be conducted to explore the underlying molecular causes of this condition.