Objective: To evaluate the relationship between urinary N-telopeptide with spinal cord injury (SCI) severity and the development of heterotopic ossification (HO). Design: Retrospective study. Setting: Acute Model Spinal Cord Injury System inpatient rehabilitation service. Participants: SCI patients admitted to acute rehabilitation. Interventions: Chart review was performed for 19 patients admitted between February 3, 2006, and December 27, 2006, with a diagnosis of acute SCI. Main Outcome Measures: American Spinal Injury Association classification of SCI, urine N-telopeptide, and blood creatinine testing was performed on admission, and clinically significant HO confirmed by triple-phase bone scans. Results: N-telopeptide and creatinine ratio was significantly higher in the HO group (311.52±193.53 vs 141.78±132.69, P=.04) and in those with complete injury (245.34±191.53 vs 105.47±61.98, P=.04). Conclusions: Based on preliminary data, N-telopeptide and creatinine ratio show some promise as a clinically useful indicator for HO in the acute phase of SCI. It may show utility as an index for early prevention of HO formation in SCI patients. N-telopeptide is also higher in the subjects with complete SCI, suggesting bone resorption is greater in this group.