As part of a larger occupational exposure study in which the concentrations of 18 elements were measured in head hair and toenail collected from steel plant workers, a number of factors associated with interpreting the data obtained were examined. In this paper, some of the limitations and complications associated with hair and nail analysis that were thereby recognised are discussed. Data obtained from the occupational study demonstrated the potential for misinterpreting hair or nail analysis data either through describing results averaged over a group by arithmetic instead of geometric means or through not accounting for the age range of subjects in groups to be compared. Examples that arose from the study indicated that differences between hair from the same subjects grown at different times can both complicate and assist in interpreting hair analysis results. In an investigation into the addition and removal of metallic powders, it was found that both hair and nail can directly incorporate elements through contact with dust.