In order to evaluate MR reliability in the therapeutic approach to lumbar disk herniation, 51 patients were examined. MR images revealed disk herniation with integrity of posterior longitudinal ligament in 25 subjects. These patients were then examined with diskography, that confirmed MR diagnosis in 23/25 cases. Percutaneous diskectomy according to Onik was successfully performed in 23/25 patients. MR imaging appears as a non-invasive method which allows exhaustive analysis of all components of lumbar spine, yielding reliable information for choosing the appropriate treatment.