The user interface of an electronic patient record system can significantly improve user acceptance and ease its adoption process. The design of a user interface should take into consideration the characteristics and the needs of the user incorporating usability engineering principles in the lifecycle of its development. In this paper we describe a study of physician interaction with a paper-based patient record system and a graphical-based electronic patient record system. The usability attributes of learnability, efficiency and satisfaction are evaluated on the whole spectrum of physicians' activities with patient record systems. The results of the study did not reveal a significant difference in the overall time to complete typical physician tasks. However, on average physicians can perform viewing tasks faster, documenting tasks slower and ordering tasks at about the same speed on the graphical-based system than on the paper based system. Physicians were found to be significantly more satisfied with the graphical-based system than with the paper-based system. The results also revealed that physicians with higher levels of computer literacy and typing skills can complete typical tasks in significantly less time on a graphical-based system than physicians with lower levels of computer literacy and typing skills.