Twenty-five normal subjects were studied by acridine orange reverse (RFA) banding in order to obtain a preliminary estimate of the type and frequency of variations in color and length. Color variations were classified into 1 of 6 colors and size variations into 1 of 5 levels. The same cells were also studied by Q banding. Acridine orange reverse banding was found to be more useful than Q banding for characterizing variations in chromosomes 14, 15, 21 and 22. In addition, it was found that there was no consistent relationship between pale or bright Q banding and the various colors observed with RFA banding. For the optimal characterization of a chromosomal variation, multiple banding technics, including RFA banding, are necessary.