BACKGROUND Narrowband UVB (NB-UVB) phototherapy is considered an accepted therapy for vitiligo. OBJECTIVE We sought to estimate the effectiveness of NB-UVB in patients with vitiligo, identify predictive factors of response, and assess the stability of NB-UVB-induced repigmentation. METHODS In all, 70 patients with vitiligo were treated twice weekly with NB-UVB. RESULTS Cosmetically acceptable (>75%) repigmentation was achieved in 34.4% of patients with lesions on the face and in 7.4% of patients with lesions on the body. Patients with phototypes III to V had a greater chance to achieve greater than 75% repigmentation on the face. Patients who responded in the first month of treatment were more likely to achieve better repigmentation rates. Repigmentation was stable in 14.3% of patients 4 years after cessation of treatment. CONCLUSIONS The study was uncontrolled. Treatment frequency was twice weekly. These results may not be representative of different treatment regimens. CONCLUSIONS Patients with vitiligo who have lesions on the face, darker phototypes, and early response to treatment have a greater chance to achieve satisfactory repigmentation after NB-UVB phototherapy.