The purposes of this study were: (1) to examine the degree and sources of uncertainty, (2) to examine the coping methods used, (3) to examine the relationship between uncertainty and coping method, for hospitalized patient with myocardial infarction. Sixty-five subjects in a teaching hospital participated in this study. Chinese Version of Mishel's Uncertainty in Illness Scale and Revised Ways of Coping Checking List were used. The results showed that myocardial infarction patients experienced moderate uncertainty. The major source of uncertainty was ambiguity due to illness, treatments, symptoms, and activities etc. Education and sex were significantly related to uncertainty. Subjects with lower education and female had higher ambiguity. The coping method most often used by subjects was problem-focused coping. The least often used one was avoidance. Generally, subjects used more problem coping than emotion coping. Finally, a significant relationship between uncertainty and emotional coping was found. These finding support that illness is inherent with uncertainty, especially life threatening illness, and uncertainty in habits the utilization of problem coping which result in using emotion coping.