Background: Uterine leiomyoma is a common gynaecological condition among Blacks. It impacts negatively on the quality of life and reproductive health of our women. Currently, the effective treatment is surgical with its attendant financial costs and complications. Women in our environments have aversion for surgery. Efforts are on to identify biochemical changes that could be responsible for this pathology with the hope that when corrected, uterine leiomyoma could be prevented or treated. Vitamin D has been reported to play important role in the development and progression of this tumour. Clinical studies comparing serum vitamin D levels in women with and those without uterine leiomyoma are few and mostly with non-conclusive findings. Aims and Objectives: To compare the serum vitamin D levels of women with uterine leiomyoma and those without uterine leiomyoma. Research Methods: This study was a hospital-based case-control study among consenting women who presented to the gynaecology clinic of Nnamdi Azikiwe University Teaching Hospital, Nnewi between October 2018 and May 2019 (8 months). Ethical approval was obtained before commencing the study. The cases were 75 women who have uterine leiomyoma while the controls were 75 age and parity matched subjects without uterine leiomyoma. Their demographic details, brief medical history and findings on physical examination were obtained and recorded in a proforma. Blood samples were collected from each participant and the serum vitamin D levels determined using the ELISA method. The volumes of the uterine leiomyomas were determined by ultrasound scan and by water displacement method following myomectomy. The data were analysed using the Statistical Package for Social Sciences (SPSS) version 23 (IBM Corp 2015). Data were presented in tables and charts. Continuous data were presented in mean and standard deviation. Categorical variables were analysed using Chi-square tests where appropriate, while continuous data were analysed using T-test. The statistical significance was inferred at P- value ≤0.05.