Head injury results in a wide range of functional sequelae. Thus, measuring solely physical aspects of functioning may fail to highlight the actual level of disability. This study compares a commonly used measure of physical disability, the Barthel Index, with three recently devised measures-the OPCS Scales of Disability, the Functional Independence Measure (FIM) and Functional Assessment Measure (FIM + FAM). Fifty-four head-injured subjects were assessed following discharge from an in-patient rehabilitation unit utilizing each measure. The majority of subjects had no detectable disability according to the Barthel Index. In contrast, only four subjects (7%) attained maximal scores for independence with the OPCS scale; two (4%) with the FIM and only one subject (2%) with the FIM + FAM. This reflected the nature of the disabilities in activities such as intellectual functioning, communication, behaviour and wider aspects of mobility measured by the OPCS, FIM and FIM + FAM but not in the Barthel Index. The relationship between all measures was significant (Spearman ranked correlations P < 0.001) but correlations were greater between OPCS, FIM and FIM + FAM than with the Barthel. The results of this study would support considering the use of scales other than the Barthel Index when describing disability following traumatic head injury.