This trial aimed to examine the effect of whey protein hydrolysate intake before and after exercise sessions on endurance performance and recovery in elite orienteers during a training camp. Eighteen elite orienteers participated in a randomized controlled intervention trial during a 1-week training camp (13 exercise sessions). Half of the runners (PRO-CHO) ingested a protein drink before (0.3 g kg-1) and a protein-carbohydrate drink after (0.3 g protein kg-1 and 1 g carbohydrate kg-1) each exercise session. The others ingested energy and time-matched carbohydrate drinks (CHO). A 4-km run-test with 20 control points was performed before and on the last day of the intervention. Blood and saliva were obtained in the mornings, before and after run-tests and after the last training session. During the intervention questionnaires were fulfilled regarding psychological sense of performance capacity and motivation. PRO-CHO, and not CHO, improved performance in the 4-km run-test (interaction p<0.05). An increase in serum creatine kinase was observed during the week, which was greater in CHO than PRO-CHO (interaction p<0.01). Lactate dehydrogenase (p<0.001) and cortisol (p=0.057) increased during the week, but the change did not differ between groups. Reduction in sense of performance capacity during the intervention was greater in CHO (p<0.05) than PRO-CHO. In conclusion, ingestion of whey protein hydrolysate before and after each exercise session improves performance and reduces markers of muscle damage during a strenuous 1-week training camp. The results indicate that protein supplementation in conjunction with each exercise session facilitates the recovery from strenuous training in elite orienteers.