This study investigated the relationship between lean management strategy and competitive performance of teaching hospitals in South-South, Nigeria, using organizational culture as a moderator. It was hypothesized that lean management strategy (continuous improvement, top management commitment and employee involvement) do not have significant relationship with competitive performance (cost effectiveness and quality). 175 respondents participated in this study, they were drawn from 10 teaching hospitals in the region. Descriptive statistics, Spearman’s rank order correlation and partial correlation techniques were used to analyse data. Results suggested that higher levels of continuous improvement, top management commitment and employee involvement are associated with higher levels of cost effectiveness and quality, while organizational culture amplifies the competitive performance benefits of lean management. It was recommended that the management of teaching hospitals should (i) continuously improve the health protocols by targeting at the layout, inventory, processes and methods to support and promote lean adoption.