Familial amloidosis, Finnish type (FAP IV) was identified clinically in an American kindred with Scandinavian ancestry. A polymerase chain reaction (PCR)-based DNA diagnostic assay was used to identify a G-to-A mutation at position 654 of the gelsolin cDNA (G654A) in this family. Molecular diagnostic testing demonstrated the mutation in individuals in three generations — the clinically affected proband, her deceased clinically affected father, and her presumably affected presymptomatic child. This report represents a rare example of FAP IV and the G654A mutation identified in a family outside Finland. The disease-associated haplotype was similar to that observed in Finnish FAP IV families (suggesting common distant ancestry).