Background: Vitiligo is a common idiopathic disorder featured by depigmented epidermis and hair follicles. It has been demonstrated that cases with vitiligo are often associated with vitamin B12 (cobalamin) deficiency. Vitamin B12 is a main determinant of homocysteine (Hcy) level. High values of Hcy are reported to be associated with toxic effects on melanocytes, which ultimately end in vitiligo. Objective: This study aimed to assess serum level of Hcy and vitamin B12 in vitiligo patients and to detect their correlation with disease activity and severity. Patients and Methods: This was a case-controlled study conducted on 50 vitiligo patients and 50 healthy controls. General and dermatological examinations were made. Serum levels of vitamin B12 and Hcy were assessed. The severity of the disease was assessed by Vitiligo Area Scoring Index (VASI) score. Results: There was a highly statistically significant increase in serum Hcy and a highly statistically significant decrease in vitamin B12 in the case group compared to the control group. There was a statistically significant relationship between serum Hcy and both VASI, duration of the studied cases, both sexes, and vitiligo type. Conclusion: Our study revealed a significant correlation between serum Hcy and both disease activity and severity (VASI). This might indicate that Hcy can be utilized as a useful marker for activity and severity of vitiligo. There was a statistically significant negative correlation between vitamin B12 and severity of vitiligo (VASI score). This might indicate that vitamin B12 can be utilized as a useful marker for severity of vitiligo.