Abstract: Systematic reviews suggest that narrowband ultraviolet B light combined with treatments such as topical corticosteroids may be more effective than monotherapy for vitiligo. Objective To explore the clinical effectiveness and cost-effectiveness of topical corticosteroid monotherapy compared with (1) hand-held narrowband ultraviolet B light monotherapy and (2) hand-held narrowband ultraviolet B light/topical corticosteroid combination treatment for localised vitiligo. Design Pragmatic, three-arm, randomised controlled trial with 9 months of treatment and a 12-month follow-up. Setting Sixteen UK hospitals – participants were recruited from primary and secondary care and the community. Participants Adults and children (aged ≥ 5 years) with active non-segmental vitiligo affecting ≤ 10% of their body area. Interventions Topical corticosteroids [mometasone furoate 0.1% (Elocon ® , Merck Sharp & Dohme Corp., Merck & Co., Inc., Whitehouse Station, NJ, USA) plus dummy narrowband ultraviolet B light]; narrowband ultraviolet B light (narrowband ultraviolet B light plus placebo topical corticosteroids); or combination (topical corticosteroids plus narrowband ultraviolet B light). Topical corticosteroids were applied once daily on alternate weeks and narrowband ultraviolet B light was administered every other day in escalating doses, with a dose adjustment for erythema. All treatments were home based. Main outcome measures The primary outcome was self-assessed treatment success for a chosen target patch after 9 months of treatment (‘a lot less noticeable’ or ‘no longer noticeable’ on the Vitiligo Noticeability Scale). Secondary outcomes included blinded assessment of primary outcome and percentage repigmentation, onset and maintenance of treatment response, quality of life, side effects, treatment burden and cost-effectiveness (cost per additional successful treatment). Results In total, 517 participants were randomised (adults, n  = 398; and children, n  =  119; 52% male; 57% paler skin types I–III, 43% darker skin types IV–VI). At the end of 9 months of treatment, 370 (72%) participants provided primary outcome data. The median percentage of narrowband ultraviolet B light treatment-days (actual/allocated) was 81% for topical corticosteroids, 77% for narrowband ultraviolet B light and 74% for combination groups; and for ointment was 79% for topical corticosteroids, 83% for narrowband ultraviolet B light and 77% for combination. Target patch location was head and neck (31%), hands and feet (32%), and rest of the body (37%). Target patch treatment ‘success’ was 20 out of 119 (17%) for topical corticosteroids, 27 out of 123 (22%) for narrowband ultraviolet B light and 34 out of 128 (27%) for combination. Combination treatment was superior to topical corticosteroids (adjusted risk difference 10.9%, 95% confidence interval 1.0% to 20.9%; p  = 0.032; number needed to treat = 10). Narrowband ultraviolet B light was not superior to topical corticosteroids (adjusted risk difference 5.2%, 95% confidence interval –4.4% to 14.9%; p  = 0.290; number needed to treat = 19). The secondary outcomes supported the primary analysis. Quality of life did not differ between the groups. Participants who adhered to the interventions for 〉  75% of the expected treatment protocol were more likely to achieve treatment success. Over 40% of participants had lost treatment response after 1 year with no treatment. Grade 3 or 4 erythema was experienced by 62 participants (12%) (three of whom were using the dummy) and transient skin thinning by 13 participants (2.5%) (two of whom were using the placebo). We observed no serious adverse treatment effects. For combination treatment compared with topical corticosteroids, the unadjusted incremental cost-effectiveness ratio was £2328.56 (adjusted £1932) per additional successful treatment (from an NHS perspective). Limitations Relatively high loss to follow-up limits the interpretation of the trial findings, especially during the post-intervention follow-up phase. Conclusion Hand-held narrowband ultraviolet B light plus topical corticosteroid combination treatment is superior to topical corticosteroids alone for treatment of localised vitiligo. Combination treatment was relatively safe and well tolerated, but was effective in around one-quarter of participants only. Whether or not combination treatment is cost-effective depends on how much decision-makers are willing to pay for the benefits observed. Future work Development and testing of new vitiligo treatments with a greater treatment response and longer-lasting effects are needed. Trial registration Current Controlled Trials ISRCTN17160087. Funding This project was funded by the National Institute for Health Research (NIHR) Health Technology Assessment programme and will be published in full in Health Technology Assessment ; Vol. 24, No. 64. See the NIHR Journals Library website for further project information.