This study evaluates the effect of audit selection regime on audit market concentration in Nigeria. It used cross sectional data collected from 91 non-financial firms quoted on the Nigerian Stock Exchange. The independent variables used for the study are, audit rotation, audit tendering and audit switching. Audit market concentration is the dependent variable. The data collected were analysed using descriptive statistics, correlation and regression analysis (white). The result finds that audit rotation, audit tendering and audit switching have significant effect on audit market concentration in Nigeria. The study therefore concludes, that audit selection regime has significant effect on market concentration and recommend that regulatory agencies in Nigeria should make policy that will regulate the audit selection regime in other to reduce the dominance of the big four audit firms and restrict the switching from one big four to another big four, thereby giving the non-big four audit firm opportunity to reducing the audit market concentration.
