We have found that the pigmentation mutant light ear in the mouse has a striking effect on lysosomes in the kidney. Male mice homozygous for the le mutant allele have a 4-fold elevated concentration of kidney beta-galactosidase (EC 3.2.1.23). The abnormal elevation of kidney beta-galactosidase is the net result of two processes. First, beta-galactosidase is elevated due to the defective urinary secretion of lysosomal enzymes which is a specific effect of the le mutation. Secondly, this effect is most evident in males and testosterone-treated females because of the induction of beta-galactosidase synthesis by testosterone, which occurs in +/+ as well as in mutant mice. The pale-ear mutation (ep) which mimics the pigmentation phenotype of le also has a similar effect on kidney lysosomes.