The incidence of the various classes of C-band and Q-band polymorphisms on ten pairs of chromosomes in the human complement have been investigated in three Scottish populations, two from the mainland (newborn and 14 year olds) and one, of individuals over 65 years, from an island in the Outer Hebrides. Although there is an overall similarity between the populations, there are some differences, especially with the island group. For all populations, over 90% of the C-band size variants fall within the medium class. Rather more variation is found in the Q-band intensity polymorphisms: the island population appears to have fewer Brilliant and Intense variants than do the other two groups, 2-9 per person as compared to 4-2 and 3-9 for the newborn and 14 year olds respectively; this may be an age difference rather than a population difference.