The purpose of this study was to analyze 42 patients disabled with low-back pain in order to assess (1) Minnesota Multiphasic Personality Index (MMPI) changes before and after surgery, (2) the predictive value of MMPI, (3) the results of anterior lumbar fusion in one group of severely disabled lumbar low-back pain patients. Statistical analyses were performed to compare and contrast MMPI, pain assessment, functional and occupational levels, and disability index before and after surgery. The degree of morbidity of the patients preoperatively was severe. After surgery, the majority of the patients showed improvement in their overall status. The available evidence suggests the following: (1) Improvement in physical condition can produce improvement in psychological test scores; (2) The preoperative MMPI is not a reliable indicator of surgical success.