The purpose of this study was to investigate the effects of an Internet-based cognitive-behavioral intervention with telephone support for chronic back pain. Participants who met the criteria for chronic back pain (N=56) were randomly assigned to either an Internet-based cognitive behavioral self-help treatment or to a waiting-list control condition. The study period lasted 8 weeks and consisted of 1 week of self-monitoring prior to the intervention, 6 weeks of intervention, and 1 week of post-intervention assessment. Treatment consisted of education, cognitive skill acquisition, behavioral rehearsal, generalization and maintenance. The dropout rate was 9% (N=5). Results showed statistically significant improvements in catastrophizing, control over pain and ability to decrease pain. Some improvement was found in both the control group and the treatment group. A follow-up of 3 months after treatment termination was completed in 92% (N=47) of the participants who completed the treatment intervention. Follow-up results showed that some improvement was maintained. Findings indicate that Internet-based self-help with telephone support, based on established psychological treatment methods, holds promise as an effective approach for treating disability in association with pain.