Abstract The paper contributes to the literature on integration of stock markets by addressing the issue of non-synchronous trading. We argue that controlling for time differences in trading hours of stock markets is important and show that time-adjustment improves estimates of market integration. We also show that using weekly frequency does not sidestep the consequences of the time-match problem but leads to significant loss of information. We show that the nature of integration of stock exchanges operating in the Czech Republic, Hungary, and Poland with the stock markets of Germany, UK and US in the period 1994–2004 is very dynamic. Finally, the study shows that the autocorrelation of returns on the main market indices of these emerging markets have declined over time.