This research investigates diversification possibilities of the four West Balkan capital markets: Sarajevo, Banja Luka, Zagreb and Belgrade Stock Exchanges. Although these markets are highly segmented with different regulations, the capital flow between them is without constraints. By analyzing six main stock market indices in a 34-month period, from 2006 till 2008, we found low to medium positive statistically significant correlation between indices returns pairs. Even though the analyzed period included the second half of 2008, when the ongoing financial and economic crisis became global, the results are encouraging. By Markowitz portfolio selection process, the diversification effect was proven on the analyzed capital markets.