This paper examines the relationship between ownership concentration and corporate performance amongst listed South African industrial firms. The study‘s theory base is rooted in the principal-agent problem and seeks to investigate the theory‘s applicability to the South African context. Descriptive statistical analysis is performed in line with existing studies (Demsetz&Lehn, 1985; Demsetz&Villalonga, 2001; Morck et al., 1988). The percentage sums of the five and ten largest shareholders as well as firm market capitalisation are treated as independent variables. The financial measures of Tobin‘s Q and return on capital employed (ROCE) form the dependent variables as a basis for measuring firm financial performance. The results suggest that there is no statistically significant relationship between ownership concentration and firms‘ financial performance in the case of Tobin‘s Q or ROCE during the survey period. However, a statistically significant positive relationship between firms‘ market capitalisation and financial performance is found. The study tentatively suggests that the separation of ownership from control does not appear to have any negative behavioural implications for the theory of the firm in the South African context. Future research is encouraged to confirm these results.