Decisions made by physicians in intensive care medicine are often complex, requiring the consideration of information that may be incomplete, ambiguous, or even contradictory. Under conditions of complexity and uncertainty, individuals may cope by using simplifying decision strategies. The research described in this paper examines the strategies used by physicians in coping with complexity in decision making. Six residents (intermediates) and three specialists in intensive care were each presented with 12 cases of intensive care respiratory problems of varying levels of complexity. The subjects were asked to think-aloud as they worked through the problems and provided a management and treatment plan for each case. The audiotaped protocols were coded for key process variables in decision making and problem solving. Despite the incompleteness and ambiguity of the information available, the confidence of physicians in their decision making was consistently high. The strategies used by intermediates and experts in dealing with the more complex cases varied considerably. Expert physicians were found to focus on the assessment of the decision problems to a greater extent than intermediates. Implications for research in decision making and medical cognition are discussed.