A prospective clinical trial was conducted involving patients with prolapsed lumbar intervertebral disk proven myelographically, who had anterior diskectomy and disk replacement with a titanium-mesh block implant. A pilot study was done in 1971 on six patients. In this trial, 28 patients were operated on with informed consent. Twenty-three had a minimum of five years' follow-up study. There were 14 men and boys, and nine women and girls. The average follow-up period was eight years and four months (range, five to 12 years three months). The average age at operation was 36 years four months (range, 13-66 years). Symptomatic improvement were divided into three groups. Sixteen patients were in Group 1, three in Group 2, and three in Group 3. Flexion-extension radiographs showed 14 patients with no movement between the vertebral bodies adjacent to the operated disk, five with minimal movement, and four with definite movement. At the implant-bone interface, no radiolucent zone was seen in 18 patients, and a definite radiolucent zone was seen in five. Twenty implants were intact, three implants had developed a crack, and three were deformed. There were no complications. The titanium-mesh block implant is an effective substitute for autogenous bone grafting in interbody fusion.