The diagnostic value of pain mapping in patients with lumbago sciatica and herniated intervertebral discs is evaluated, somatosensory pain descriptions being compared with surgical findings. Information has been extracted from complex data sets using a multivariate data analysis program (FCVPC-87). Superficially experienced pain may represent pronounced nerve root affliction. Pain relief in particular body positions was related to extruded discs and additional osseous stenosis, and rarely occurring relief to derangement of nerve root circulation. Neither somatosensory pain quality descriptions nor pain intensity variables were found to be of diagnostic value. Long duration of symptoms was found together with nerve root atrophy. Affliction of the L5 and S1 nerve roots showed differences with regard to pain localization and intensity and some surgical findings. Pain mapping may represent an indication of the patho-anatomical substratum in patients with herniated lumbar intervertebral discs.