Many claims have been made about the consequences of not documenting design rationale. The general perception is that designers and architects usually do not fully understand the critical role of systematic use and capture of design rationale. However, there is to date little empirical evidence available on what design rationale mean to practitioners, how valuable they consider it, and how they use and document it during the design process. This paper reports a survey of practitioners to probe their perception of the value of design rationale and how they use and document the background knowledge related to their design decisions. Based on 81 valid responses, this study has discovered that practitioners recognize the importance of documenting design rationale and frequently use them to reason about their design choices. However, they have indicated barriers to the use and documentation of design rationale. Based on the findings, we conclude that further research is needed to develop m...