An earlier paper presented at an ERES conference (Maier et al., 2010) provided evidence that energy efficient improvements in residential properties were not capitalized into prices suggesting that the Austrian residential markets are not efficient. In this paper, we further shed light on this issue by formally testing for the efficiency of the residential markets in Austria. The concept of efficiency has been examined in the literature mainly based on Famaís (1970, 1976) three versions of the Efficient Market Hypothesis (EMH). Our strategy is to use the weak form and the semi-strong form specifications of the EMH to examine if information about past prices and other market fundamentals are already incorporated into the present prices of residential units. We use aggregate house price data published by the Austrian National Bank. To the best of our knowledge, the present study is the first such analysis for Austrian residential markets.