The aim of our study was to compare the efficacy of azathioprine in combination with NB-UVB and NB-UVB monotherapy in advanced nonsegmental vitiligo. 60 patients with advanced nonsegmental vitiligo were included in the study and divided in 2 groups, 30 patients each. Group A received azathioprine 50 mg daily in combination with NB-UVB, group B received NB-UVB monotherapy. The efficacy was assessed using the VASI (vitiligo prevalence index) and DLQI (dermatological quality of life index) score. All 60 patients completed the study and were included in the final analysis. Among the patients receiving the azathioprine + NB-UVB combination a statistically more significant decrease in the activity and extent of the skin process. The average VASI score changed from the beginning to 24 weeks by -2.65 points (95% CI from -4.91 to -0.28, p<0.001) in Group A and by -0.71 (95% CI from -1.08 to -0.33, p<0.001) in Group B. The average DLQI score changed by -7.83 points (95% CI from -9.29 to -6.38, p<0.001) in Group A and by -3.33 (95% CI from -4.48 to -2.18, p<0.001) in Group B. The change in VASI score reached significance from week 16 (-2.51, p=0.01), and that in DLQI score from week 8 (-2.76, p=0.005). In Group A, only 4 of 30 patients developed new foci of vitiligo during the 6 months of therapy, compared with 13 of 30 patients in Group B. Thus, the NB-UVB and azathioprine combination showed greater efficacy in stopping the disease activity, the degree of spread and severity of vitiligo, as well as in improving the quality of life of patients. Azathioprine is well tolerated by patients and has a low spectrum of side effects, which allows to successfully use the drug to stabilize vitiligo. Azathioprine also promotes faster re-pigmentation of the lesions, requiring fewer phototherapy sessions.