In order to further investigate the paternal-age effect on meiotic non-disjunction rates for the chromosomes 14 and 21, we examined spermatozoa from three men aged > 60, using multicolour fluorescent in-situ hybridization (FISH). More than 10,000 sperm cells were analysed for each of the three subjects (A, B and C), by simultaneously hybridizing two YAC probes specific for chromosomes 14 and 21 respectively using two-colour FISH. The results show that the disomy 21 rates observed in the spermatozoa of two out of the three men aged > 60 years were higher (1.02 and 1.17% respectively) than the rates observed in eight control adults aged < 30 years (mean frequency 0.48%) analysed under similar conditions. These results suggest that there may be a small effect of age on male non-disjunction rates for chromosome 21. However, before any firm conclusions could be drawn, a much bigger sample of older men would have to be compared with a paired control population using the same FISH experimental approach.