['There have been only a few structural brain-imaging studies, with varied findings, of opiate-dependent subjects. Voxel-based morphometry (VBM) is suitable for studying whole brain-wise structural brain changes in opiate-dependent subjects.', 'The objective of the current study is to explore gray matter density in opiate-dependent subjects.', 'Gray matter density in 63 opiate-dependent subjects and 46 age- and sex-matched healthy comparison subjects was compared using VBM.', 'Relative to healthy comparison subjects, opiate-dependent subjects exhibited decreased gray matter density in bilateral prefrontal cortex [Brodmann areas (BA) 8, 9, 10, 11, and 47], bilateral insula (BA 13), bilateral superior temporal cortex (BA 21 and 38), left fusiform cortex (BA 37), and right uncus (BA 28).'] Does prefrontal and temporal gray matter density decrease in opiate dependence?