This paper examines whether board gender diversity affects the selection of auditor industry expertise in medical foundations. The empirical results show that female director ratios do not have a significant effect on the choice of auditor industry expertise. However we find out that female director ratios are nonlinearly (inverted U-shape) related to the selection of auditor industry expertise. That is, medical foundations with higher female director ratios, in the premise of not more than one-third, are more likely to choose auditor industry expertise compared to their peers. These findings provide an incremental contribution to the literature on board gender diversity and selection of auditor industry expertise.