This study has been conducted to identify and describe conceptual systems of uncertainty using qualitative data from a written association test with open ended questions of "Please list three items in order, as they occur to you, when you think about uncertainty". Two open ended questions were added to help the grouping process of the concepts to be more reliable. 336 listed words were collected from 53 non-patients(nurse, professionals, nurse-students, students) and 65 patients. And data analysis involved three levels of increasing complexity and abstractedness, which involved a grouping process of "concept" with "meaning and value" to encompass a more abstract grouping with greater scope. The initial level grouping of the 336 listed words yielded 28 distinct categories: change, time, life, health and illness, relationships, family and person, event, trenscendental being, luck, hope and expection, positive emotion, negative emotion, action, self, nature, information, society, success and failure, non-predictiveness, anxiety, conflict, powerlessness, vagueness certainty not known, undoubtful, incorrectness, undetermined, indefinite. In the 2nd level of abstraction with 28 distinct categories, change/ time/ life/ health and illness/ relationships/ family and person/ event/ trenscendental being classified under the category of objectivity of uncertainty. Self under the category of subjectivity of uncertainty. Luck/ hope and expection/ positive emotion/ negative emotion/ and action were categorized under the category of consequences, and nature under the category of natural environment. Information/ society/ success went into the category of social environment. Unpredictability/ anxiety/ conflict/ powerlessness/ vagueness/ certainty not known/ undoubtful/ incorrectness/ undetermined/ indefinite were classified into the category of concomittent. And finally, the 3rd level of abstraction, with 7 categories, yielded 3 categories of person/ environment/concomittent. The results are significant to refine the concept of uncertainty. These understanding will facilitate the development effective methods of nursing to the uncertainty in chronic illness.