Little information is available on the forage potential of improved amaranth (Amaranthus sp.) cultivars. Our objectives were to determine the effect of maturity on forage yield and forage quality of A. cruentus L. and A. hypochondriacus L. and to evaluate forage quality of leaf, stem, and inflorescence fractions at two maturity stages. Field experiments were conducted on a Waseca silt loam (fine-loamy, mixed, mesic Cumulic Haplaquolls) and on a Waukegan silt loam (fine-silty over sandy skeletal, mixed, mesic Typic Hapludoll). Amaranth dry matter yield was 1.3 tons/acre at 8 wk after planting (WAP), increased with each subsequent harvest, and peaked at 4.4 tons/acre and 4.1 tons/acre at 16 and 14 WAP in 1988 and 1989, respectively. Forage quality decreased as maturity increased from bud to flowering. Crude protein (CP) was greatest (average of 23%) at 8 WAP when amaranth was vegetative and decreased with maturity to about 13%. Forage neutral detergent fiber (NDF) and acid detergent fiber concentrations (ADF) were about 36 and 26% at 8 WAP and increased as plants matured. Amaranth had nearly equal proportions of leaf and stem material when vegetative. When harvest was delayed until inflorescence development, the leaves averaged only 13.4% of the total forage and stems averaged 42.9%. Leaves had greater CP and less fiber concentration than stems. The decline in whole plant quality with maturity was associated with a decrease in CP concentration of leaf and stem fractions and an increase in both NDF and ADF concentrations of stems. Amaranth entries differed in forage quality, but vegetable types were not superior to grain types.