OBJECTIVE: To test the effects of telephone counseling and telemonitoring on weight loss. METHODS: A randomized-controlled trial was conducted over 18 months. Participants were assigned to an immediate or delayed-start group. The intervention included a Thin-Link((R)) home telemonitoring scale and biweekly telephone counseling over 6 months. RESULTS: The immediate group lost significantly more weight relative to the delayed group over the first 6 months (-7.5 versus +1.3 pounds) and at subsequent visits. CONCLUSION: Compared to no treatment, the intervention was effective at producing weight loss. Home telemonitoring may enhance standard weight-loss counseling.