Background The Vitiligo Extent Score (VES) has recently been introduced as a physicians' score for the clinical assessment of the extent of vitiligo, but a good patient self-assessment score is lacking. Objective The objective is to develop and validate a simplified version of the VES as a patient-reported outcome measure (PROM). Methods After extensive pilot testing, patients were asked to score their vitiligo extent twice with an interval of 2 weeks using the Self Assessment Vitiligo Extent Score (SA-VES). The scores were compared with the physicians' evaluation (VES). Results The SA-VES demonstrated very good test-retest reliability (intraclass correlation = 0.948, 95% confidence interval [CI]: 0.911-0.970) that was not affected by age, skin type, or vitiligo distribution pattern. According to patients, this evaluation method was easy to use (22% very easy; 49% easy; 29% normal) and required <5 minutes in the majority of patients (73%, <5 minutes; 24%, 5-10 minutes; 2%, 10-15 minutes). Comparison of the SA-VES and the VES demonstrated excellent correlation (r = 0.986, P <.001). Limitations Few patients had a dark skin type. Conclusion The results demonstrate excellent reliability of the SA-VES and excellent correlation with its investigator-reported counterpart (VES). This patient-oriented evaluation method provides a useful tool for the assessment of vitiligo extent.