Objective: The objective of this study was to determine the reliability of measuring wound undermining in people with spinal cord injury (SCI). Study design: A psychometric study. Setting: The study was conducted at the Indian Spinal Injuries Centre, New Delhi, India. Participants: Thirty people with a complete or incomplete SCI and a pressure ulcer with wound undermining were recruited. Methods: Wound undermining was measured using the four cardinal points from a clock face (with 12 O'clock defined as towards the head). Inter-rater reliability was tested by comparing the wound undermining scores from two different assessors. Intra-rater reliability was tested by comparing the wound undermining scores from the same assessor on two different days. Results: The intraclass correlation coefficients (95% confidence interval) for inter-rater and intra-rater reliability were 0.996 (0.992-0.999) and 0.998 (0.996-0.999), respectively. Repeat measurements by the same and different assessor were within 0.3 cm of each other, 80% and 83% of the time, respectively. Conclusion: Measurements of wound undermining have excellent reliability.