Records of 4103 scanblack mink kits born in 1989–94 were used to estimate genetic parameters for body weight and body length during the growth season with special emphasis on the suckling period. Maternal additive and direct additive effects and effects of permanent maternal and specific litter environment were estimated, using restricted maximum likelihood (REML) in univariate and bivariate animal models. The maternal additive effect was constant during the first 4 weeks after parturition ath2m≈ 0.30 for weight, and decreased thereafter. The heritability estimate for direct additive effect for body weight decreased fromh2a≈ 0.19 at birth toh2a≈ 0.12 at 4 weeks but increased toh2a≈ 0.50 in August to December. The maternal permanent environment was important only at 2 and 4 weeks,c2p≈ 0.10. The specific environment, common within the litter, increased fromc2s≈ 0.24 at birth to c2s≈ 0.40 at 2 and 4 weeks, but decreased thereafter toc2s≈ 0.10 in December. Estimates for body length showed a slightly different pattern,h2avarying from 0.07 to 0.17 in the lactation period, but increased to 0.46 at pelting. The heritability of maternal additive effect(h2m)for body length varied from 0.17 to 0.24 during the lactation period and decreased thereafter to 0.06 at pelting.