The theory of uncertainty in illness has its strongest support among subjects who are experiencing the acute phase of illness or are in a downward illness trajectory (Mishel, 1988a). The theory has not addressed the experience of living with continual, constant uncertainty in either a chronic illness or in an illness with a treatable acute phase and possible eventual recurrence. Since uncertainty characterizes many, most prevalent, long-term illness conditions, there is a need to reconceptualize the theory of uncertainty to include the experience of living with continual uncertainty. A close examination of the theoretical statements and the empirical data reported by Mishel resulted in the identification of areas of the theory that could be expanded and reconceptualized. The reconceptualization effort was primarily fueled by questions about the outcome portion of the uncertainty theory. To provide a contest for the expansion and reconceptualization of uncertainty, applicable parts of the theory are summarized below.