The rapid growth of coyote (Canis latrans) populations in Illinois since 1980 prompted a need for current demographic data to be used in population models for management. From 1994 to 1997 we examined 977 coyotes harvested by hunters and trappers throughout the state and compiled data on age structure, sex ratios, reproductive rates and physical condition. Statewide, 55% of harvested coyotes were juveniles, 20% were yearlings and 25% adults. The sex ratio did not differ from unity among juveniles and yearlings, but was skewed towards males in the adult class. The number of harvested animals decreased by 45–60% between successive classes from 0.5 through 2.5 y old, then by 30–40% through 9.5 y old. Statewide, 57% of females bred and breeders averaged 4.9 placental scars. Males were larger than females, averaging 14.1 and 12.1 kg whole body mass, respectively. Kidney fat reserves were highest in juveniles and adult females and lowest in yearlings. Femur marrow fat was generally high and did not differ among age-classes. Ovulating females were heavier than non-ovulators among juveniles and yearlings. We found that coyotes in Illinois are in good physical condition with high winter fat reserves and reproductive rates. However, reproductive rates are lower than they were in 1978–1979 when the population was rapidly expanding in the state.