The impact of delayed diagnosis of cystic fibrosis (CF) on families is poorly described, especially in the United States. Studies outside the United States indicate that misdiagnosis leads to increased anxiety, guilt, anger, and mistrust of the medical profession, and late diagnosis leads to more negative feelings about the pre-diagnostic period and less confidence in the medical profession. To describe the impact of delayed diagnosis on US families, diagnostic stories were requested on the CF Research, Inc, e-mail list in September 2003. Twenty diagnostic stories were returned, and 20 additional stories were found on the Cystic-L listserv dating back to 1997. Stories were condensed into that of a single family and a qualitative description of the symptoms, medical and family responses at different life stages provided, along with health and family sequelae if the diagnosis had occurred at various ages. Responses to symptoms differed by age. Families were frustrated and stressed by diagnostic incompetence. Ineffectual care led to long-term anxiety, emotional trauma, and self-doubt. Families suffered economic losses. Relationships with one another and with doctors were seriously affected. CF parents consistently expressed that newborn screening would help others avoid the pain they suffered by not knowing the diagnosis earlier.