A multivariate clustering procedure was used to identify replicable, homogeneous MMPI profile subgroups among three independent cohorts of male (N=233) and female (N=315) low back pain (LBP) patients. Three subgroups were replicated across all male cohorts and four subgroups were replicated across all female cohorts. Multiple discriminant analysis showed that for both male and female patients between-subgroup variability was significantly greater than within-subgroup variability. The results suggest that LBP patients may not be solely characterized by MMPI profiles featuring the "conversion V" configuration. Examination of the profile subgroups also suggests there may be distinct, pain-related, behavioral attributes associated with each subgroup which might have important implications for practitioners' choice of treatment modalities. Suggestions are made for research regarding the development of specific, optimal treatments for various LBP patient subgroups. © 1978 Plenum Publishing Corporation.