The Headturn Preference Procedure (HPP) is widely used in infant research. Previous studies have shown that speech perception measures obtained with HPP are related to later language skills which may make them a potential instrument for an early detection of developmental language risks. The present study assessed the reliability and stability of this measure by testing 6-month-old German-learning infants with the HPP in three sessions each separated by 1 week. Significant correlations were found between the overall looking times across test sessions but not between the differences in looking times for different test conditions. The results underline limitations but also the potential of using early speech perception measures as diagnostic tools.