In this paper, we study the international and sectoral diversification potential in real estate portfolios. Building on a unique dataset of direct real estate markets covering 16 OECD countries over the period 1999–2018, we introduce a statistical test to compare country-level and sector-level diversification potential. This new diversification test provides investors and analysts with a valuable tool as it delivers both estimates and robust significance levels. The empirical findings for real estate investments broadly reveal that international diversification dominates sectoral diversification.