Based on the resource based view theory (RBV), this study examines the association between buying firms’ cross functional integration, buyer-supplier integration and supplier logistics performance in buyer-supplier relationships. RBV considers these two dimensions of supply chain integration as strategic resources which play an important role in improving logistics performance. This research examines the effects of both intra-firm integration and inter-firm integration on supplier logistics performance with survey data from key informants in the public medicine supply system in Mainland, Tanzania. The unit of analysis is the purchasing relationship between public health facilities and a focal supplier acting as public agent of the Medical Stores Department (MSD). The empirical analysis is based on data from 166 purchasing managers and demonstrates that buyer-supplier integration improves supplier logistics performance significantly. There is no main effect of the buying firm’s cross functional integration on supplier logistics performance, but more extensive cross functional integration in the buying firms improves the effect of buyer-supplier integration on supplier logistic performance significantly, and indicates that extensive cross functional integration in the buying firms provides an administrative