Noninbred mice of the ICR colony were studied by a set of characters making it possible to estimate the range of genetic polymorphism in the given population. Genotypes of mice for loci A-, B-, D-, S-, PP, Se Se, and cc were determined. Noninbred mice were polymorphic for loci A, B, D, and S. Frequencies of recessive alleles of loci A, B, and D was calculated. Noninbred mice have a high fecundity and a low level of embryonic mortality, which indicate population heterogeneity. The age of the mother was shown to have no effect on the ovulation norm. The population standard of the colony for age-dependent change in the body weight and size was established. Age-dependent survival in females and males was shown to be associated.