This study investigates the link between bank concentration and interest rate pass-through (IRPT) in four sub-Saharan countries. It also analyses whether there is asymmetry in IRPT and whether such asymmetry is related to changes in bank concentration. By applying a number of econometric methods including Asymmetric Error Correction Models, Mean Adjustment Lag (MAL) models and Autoregressive Distributed Lag models on monthly data for the period 1994-2007, the study found some evidence of a relationship between bank concentration and IRPT in all four countries. However, the results reveal that bank concentration has a stronger influence on the magnitude of its adjustment rather than its speed. Of particular note in this investigation is the fact that the findings support both the Structure-Conduct-Performance hypothesis and the competing Efficient-Structure hypothesis in the banking industries of the four countries. While there is some evidence supporting the view that bank lending and deposit rates adjust asymmetrically to changes in policy rates, there is very limited evidence that these asymmetries are a result of bank concentration. The key implication of the result for African countries is that increased bank concentration through bank consolidation programmes designed to strengthen banking industries should not be viewed with cynicism in so far as monetary policy transmission is concerned because concentration does not necessarily undermine the effectiveness of monetary policy.