This study compares a comprehensive method of collecting injury data from sports medicine clinics, with a more simplified method of injury surveillance. The sports medicine injury surveillance (SMIS) project was implemented in a group of five allied sports medicine clinics in Melbourne. over two consecutive years. The injury surveillance method used in the second year (SMIS2) was a simplified version of that used in the first year (SMIS1). Methodological differences in the injury surveillance systems included form design, staff commitment and training, auditing process, financial incentives offered and employment of a project officer. Data were collected on 6479 new sports injury patients during SMIS1 and on 1682 patients during SMIS2. Comparative data from the two years of injury surveillance included patient profile (gender. age. days from injury to treatment, sport and context of injury) and injury information (site, cause and nature of injury). The SMIS2 methodology was associated with a lower sensitivity (p < 0.001) and a higher proportion of missing information (p < 0.001) than the SMIS1 methodology. There was also a significant difference in the nature and cause of injury variables (p < 0.001) between SMIS1 and SMIS2 and this was associated with coding changes. This study shows that the method of data collection influences both the proportion of missing information and the sensitivity of the system. A comprehensive method of injury surveillance will lead to a more complete data collection process. Methodological differences, however, do not appear to substantially alter conclusions about general patient characteristics, but do have some influence on the accuracy with which broad injury data are identified. Notwithstanding these comments, this study shows that injury surveillance activities can be successfully implemented in sports medicine clinics.