The aim of this study was to prospectively make a survey of injuries in junior players from a Swedish local tennis club during a 2-year period in relation to gender, anatomic location, month of the year when injured, injury type and injury severity. All 12-18 years old members in a tennis club playing more than twice weekly were asked to participate. Fifty-five junior tennis players, 35 boys and 20 girls accepted to participate. All tennis-related injuries were prospectively registered and evaluated. Time of exposure for playing tennis was recorded. Thirty-nine players sustained 100 injuries, 73 in boys and 27 in girls. Injury incidence for boys was 1.7 injuries/1000 h of tennis playing time and for girls 0.6 injuries/1000 h. Ankle sprains, low back pain and knee injuries were the most common ones. Sixty-five percent were new injuries, and the majority of these injuries were located at the knee joint followed by the ankle joint, while most of the recurrent injuries were found in the lumbar spine. Boys suffered mainly from low back pain and ankle injuries and girls from low back pain and knee injuries. Forty-three percent of the injuries caused absence from tennis for more than 4 weeks and 31% more than 1 week.