Rabbits were fed semipurified casein diets containing either 4% or 2.5% mineral mix for 8 weeks. Both groups maintained weight throughout the experimental period. The plasma total cholesterol concentration was significantly higher after 4 weeks on diet and slightly higher after 8 weeks in animals fed the lower level of minerals. Plasma IDL- and LDL-cholesterol concentrations after 4 weeks and HDL-cholesterol concentrations after 8 weeks were significantly higher in animals fed the 2.5% compared to those fed the 4% mineral mix. Kinetic experiments showed that in rabbits fed the lower level, the fractional catabolic and production rates of VLDL-apo B were lower and a greater proportion of IDL-apo B was derived from sources other than VLDL compared to the animals fed the higher level. LDL-apo B kinetics were not significantly different between the 2 groups. These data suggest that a reduction in dietary minerals enhances casein-induced hypercholesterolemia.