INTRODUCTION: Patient-reported outcome (PRO) instruments typically are delivered via paper or computer; we validated administration of hip-specific instruments over a mobile phone software communication platform outside a clinical encounter. METHODS: Consecutive patients (n = 69) presenting to a hip preservation clinic completed the Hip Disability and Osteoarthritis Outcome Score Short Form physical function and pain subscales (HOOS-PS and HOOS-PAIN) using standard collection techniques. The subsequent day, patients completed these instruments via a text messaging software program. Text reminders were sent to encourage completion of unanswered questions. Correlation between in-office and mobile phone delivery of PROs was assessed. RESULTS: The intraclass correlation coefficient between in-clinic and mobile phone delivery of HOOS-PS and HOOS-PAIN was 0.72 (95% confidence interval, 0.58 to 0.81) and 0.80 (95% confidence interval, 0.69 to 0.87), respectively. Completion rate of 93% (64 of the 69) was observed using mobile phone and software messaging. Nine patients completed their PRO after being sent a text message reminder. Fifty-one percent of patients completed all PRO questions within 5 minutes; 26% took between 5 and 10 minutes, and 16% took 10 to 30 minutes for completion. DISCUSSION: HOOS-PS and HOOS-PAIN PRO instruments administered via text messaging with automated reminders demonstrate good to excellent reproducibility, no minimal detectable change between communication methods, and a high completion rate in adolescents and young adults with hip pain. Mobile phone delivery via automated software may be a valid method for administration of other PROs, allowing for communication with patients anytime and anywhere. LEVEL OF EVIDENCE: Level IV, case series.