Introduction: Ovarian cancer has worst prognosis and high mortality rate due to delayed onset of symptoms and lack of proper screening test that leads to late diagnosis in the advanced stages. Folate and vitamin B12 are involved in one carbon metabolism as cofactor and also has a role in conversion of homocysteine to methionine. Aberration in these processes may amplify carcinogenesis. Objective: To analyse the role of serum level of CA125, Folate, Vitamin B12 & Homocysteine as diagnostic tool in Epithelial Ovarian Cancer. Methods & Materials: 35 diagnosed cases of epithelial ovarian carcinoma were collected from Outpatient and Inpatient Department of Obstetrics & Gynaecology as per Eastern Cooperative Oncology Group performance status. Serum levels of CA125, Folate, Vitamin B12 and Homocysteine were assayed at the time of diagnosis, 3 months and 6 months post treatment. Comparison between pre and post treatment serum levels of parameters were analysed by Graph Pad Prism version 8.4.3. Results: Mean age of developing ovarian cancer is 51± 9 years. Pre-treatment Serum CA125 levels (mean 1021 ± 800.5 units/ml) & Serum Homocysteine levels (mean 11.23 ± 2.164 ng/ml) were signicantly higher than 3 months & 6 months post-treatment serum levels. Pretreatment Serum Folate levels (mean 3.231 ± 1.506 ng/ml) & Serum Vitamin B12 levels (mean 280.6 ± 140.8 ng/ml) were signicantly lower than 3 months & 6 months post-treatment serum levels. Conclusion: The serum levels of selected parameters were signicantly altered in cases of epithelial ovarian cancer & plays an important role in process of carcinogenesis