Physicians are faced with questions and uncertainties regarding information/knowledge for the best care of their patients. There are several sources of medical information available from which they can retrieve the necessary answers, such as colleagues, textbooks or software on personal digital assistants (PDA). This case study evaluates how physicians seek medical knowledge when they face a clinical challenge. Our observational study took place in one of the US Veterans Affair (VA) Hospitals, during August 2006, with combined observation of, and interviews with, physicians. Search for information was significantly different in strategy and materials used depending on location, temporality and complexity of the question.