The objective of this study was to investigate the knowledge physicians expect pharmacists to have when discussing the safety of medicines. Survey questionnaires were distributed to 81 physicians working at 2 general hospitals in the Jōetsu region of Niigata Prefecture, Japan. The survey instrument included 22 knowledge items, and for each item physicians were asked to select either “Necessary knowledge” or “Knowledge that should be understood” for pharmacists. We obtained 71 valid responses (response rate: 87.7%). Results showed that “Package inserts” were selected by most physicians: 95.8% for specialist-related inserts and 85.9% for non-specialist inserts, followed in order by “Guidelines in Japan”, “Interview forms”, “Blue letter and yellow letter”, and “Recent topics in academic meetings in Japan”. Knowledge of specialty-related fields was significantly more likely to be expected of pharmacists than non-specialty fields: 48.0% and 36.5%, respectively (p < 0.001). Overall, physicians in this study suggested that when pharmacists share information with physicians, their communications may be enhanced by referring to Japanese guidelines and relevant topics that have previously been discussed at academic meetings.