Achilles tendinopathy is a common overuse injury, especially among athletes involved in activities that include running and jumping. Often an initial period of rest from the pain-provoking activity is recommended. To prospectively evaluate if continued running and jumping during treatment with an Achilles tendon-loading strengthening program has an effect on the outcome. Randomized clinical control trial; Level of evidence, 1. Thirty-eight patients with Achilles tendinopathy were randomly allocated to 2 different treatment groups. The exercise training group (n = 19) was allowed, with the use of a pain-monitoring model, to continue Achilles tendon-loading activity, such as running and jumping, whereas the active rest group (n = 19) had to stop such activities during the first 6 weeks. All patients were rehabilitated according to an identical rehabilitation program. The primary outcome measures were the Swedish version of the Victorian Institute of Sports Assessment-Achilles questionnaire (VISA-A-S) and the pain level during tendon-loading activity. No significant differences in the rate of improvements were found between the groups. Both groups showed, however, significant (P < .01) improvements, compared with baseline, on the primary outcome measure at all the evaluations. The exercise training group had a mean (standard deviation) VISA-A-S score of 57 (15.8) at baseline and 85 (12.7) at the 12-month follow-up (P < .01). The active rest group had a mean (standard deviation) VISA-A-S score of 57 (15.7) at baseline and 91 (8.2) at the 12-month follow-up (P < .01). No negative effects could be demonstrated from continuing Achilles tendon-loading activity, such as running and jumping, with the use of a pain-monitoring model, during treatment. Our treatment protocol for patients with Achilles tendinopathy, which gradually increases the load on the Achilles tendon and calf muscle, demonstrated significant improvements. A training regimen of continued, pain-monitored, tendon-loading physical activity might therefore represent a valuable option for patients with Achilles tendinopathy.