This paper examines industry concentration for the South African manufacturing sector over the 1972-1996 period, for the three digit industry classification. The paper notes both the high level of industry concentration in South African manufacturing, and a rising trend in concentration across a wide range of industries. The paper further explores the impact that industry concentration has on a wide range of indicators of industry performance. We find that increased concentration serves to lower output growth, raise unit labour costs, and to lower labour productivity. The impact on employment, total factor productivity and investment rates based on bivariate examinations of the data are ambiguous. The paper concludes by examining the impact of concentration on employment and investment rates using a dynamic heterogeneous panel estimation methodology. We find that increased concentration unambiguously lowers employment. For investment rates, increased inequality of market share serves to raise investment rates, while falling firm numbers for any given inequality of market share lowers investment rates. The difference can be interpreted as the distinct impact that the pursuit of managerial objectives (large market share promoting further productive capacity expansion) and that market contestability (under falling numbers of firms in an industry, monopolistic incentives to curtail productive capacity rise) have on investment.