Sequential Q and acridine orange R banding were performed on 50 normal individuals to determine those individuals with the maximum number of variants by acridine orange reverse banding. In three individuals from different families, one of the two homologs of each of five pairs of acrocentric chromosomes was classified as variant. The variant present in two individuals enabled unambiguous determination of the paternal or maternal origin of all 10 acrocentric chromosomes. In the third family, the variants in the third generation were sufficient to determine the origin of homologs in 5 of 10 acrocentric chromosomes. Overall, the parental origin of 36 of 50 acrocentric chromosomes (72 %) could be determined. In no case was the pattern of variants found in offsprings and parents incompatible with Mendelian inheritance.