Uncertainty, according to the theory established by Merle Mishel, is the inability to determine the meaning of illness-related events due to lack of sufficient cues allowing patients to assign value to objects or events and accurately predict outcomes (Elphee, 2008). This author believes it is important for nurses to fully understand the whole patient and what they are experiencing when faced with a new and frightening diagnosis. It is necessary to provide patients with sufficient information regarding their diagnosis, if they wish. This author believes that uncertainty theory can help the nurse more fully understand the challenges and uncertainty the patient faces when undergoing a new diagnosis. Mishel's uncertainty theory of illness is a middle-range theory indicating that it is neither too broad nor too narrow (Noir, 2014). The theory was developed from studies of men with prostate cancer who vigilantly awaited advanced signs of their disease (Black, 2014). The theory has three main components, which integrate: antecedents of uncertainty, impaired cognitive appraisal, and management of illness-related uncertainty (Neville, 2003). The antecedents of Mishel's theory are stimulus framing, cognitive abilities, and event congruence (Neville, 2003). The stimulus framework includes three parts: symptom schema, event familiarity, and event congruence (Neville, 2003). A symptom pattern can occur when the symptoms of the illness occur consistently to form a pattern (Elphee, 2008). Familiarity of events refers to the repetitive nature of the healthcare environment and not necessarily the physical characteristics of the illness (Elphee, 2008). Elphee also defines the congruence of events as the heart of the paper......if the patient is aware. References Black, BP and Chitty, KK (2014). Professional Nursing: Concepts and Challenges (7th ed.). St. Louis, MO: Saunders. Elphee, E.E. (2008). Understanding the concept of uncertainty in patients with indolent lymphoma. Oncology Nursing Forum, 35(3), 449-454. Kazer, MW, Jr., D.E. and Whittemore, R. (2010). Stepping outside the black box: extending a theory-based intervention to self-manage uncertainty associated with active surveillance (AS) for prostate cancer. Research and Theory for Nursing Practice,24(2), 101-112.Neville, KL (2003). Uncertainty in illness: an integrative review. Orthopedic Nursing,22(3), 206-214.Suzuki Phd, RN, AOCNP, M. (2012). Quality of life, uncertainty and perceived involvement in decision-making in patients with head and neck cancer. Oncology Nursing Forum, 39(6), 541-548.