During 4 weeks of military nordic ski training with 638 men, 45 skiing injuries occurred with 359 days lost from training (5.63 injuries per 1,000 skier days). Knee injuries represented 38% of total injuries, with 58% of these being medial collateral ligament sprains. Knee injuries represented a greater fraction of total injuries in the novice skier cohort than in the experienced skier cohort. All injured subjects except one responded favorably to conservative therapy available at the training facility. Despite the special rigors of military nordic skiing, the incidence and anatomic distribution of injuries is similar to that reported with civilian skiing.