RESUMEN
BACKGROUND AND PURPOSE: No suitable scale has been identified in literature that comprehensively measure self-efficacy of Pakistani breast cancer patients. The study aimed to develop a self-efficacy scale in Urdu language and determine its dimensions. METHODS: The scale was developed with input from experts and literature. It was administered, in cross-sectional phase of two pilot studies, on breast cancer patients receiving chemotherapy. Post hoc internal consistency reliability was computed and principal component analysis (PCA) was performed. RESULTS: U-SES comprised 17 questions. PCA revealed a total of five factors explaining cumulative variance of 68.7%. These factors were self-confidence, faith, coping, optimism, and decision making. Post hoc internal consistency (Cronbach's alpha) value was high (∞ = 0.87). CONCLUSION: The self-efficacy scale has acceptable validity and reliability and has potential to obtain information related to self-efficacy of cancer patients receiving chemotherapy.