The purpose of this study was to investigate the difference in cardiopulmonary endurance among positions in middle school soccer, and to identify the incidence of sports injuries in association with soccer matches and training. Ninety-six (32 forwards, 27 defenders, 29 midfielders, and eight goalkeeper [GK]) middle school soccer players (12.77+/-0.53 years) participated in this study. They had no medical problems. Their height, weight and body mass index (BMI) were measured, and they also went through tests for maximal oxygen consumption (VO2max). We interviewed middle school soccer players about their soccer careers and their history of sports-related injuries. Physical fitness was compared among players in different playing positions. VO2max was significantly higher in forward and defender groups than GK group. There was no significant relationship in cardiopulmonary endurance among outfield players. GK were taller and heavier than outfield players. BMI was significantly higher in GK group than midfielder group. They had played soccer for 39.08+/-20.28 months on average. During matches and training, forwards suffered 13 injuries (36.1%); defenders suffered 10 injuries (27.8%); midfielders suffered 12 injuries (33.3%); and only one GK came down with an injury (2.8%). The most common types of injuries were to knees (36.1%) and ankles (33.3%).