A retrospective autopsy study during 1957 to 1983 of patients with clinically documented cystic fibrosis (CF) who were at least 15 years old at the time of death (33 patients) revealed that 11 (33%) had amyloid deposits in multiple organs. The spleen, liver, and kidneys were the principally affected organs, with microscopic deposits mainly restricted to blood vessels. Only one patient had overt clinical manifestations of organ dysfunction secondary to the presence of amyloid. No differences were noted between the groups with (11 patients) and without (22 patients) amyloidosis with respect to age at diagnosis of CF; number, severity, and types of infections; and longevity. Our data demonstrate that amyloidosis is more common in patients with CF than previously reported, and this purported increase parallels the longer life span of these patients. Those patients who are older than 15 years of age constitute the particular group at risk, and they should be evaluated for amyloidosis if unusual clinical findings emerge to suggest it. Clinically evident amyloidosis is uncommon, however, in patients with CF and amyloid deposits at this time. It is likely that clinically relevant amyloidosis will become more of a complicating factor in the future as the life span of these patients continues to increase.