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Desert bighorn sheep (Ovis canadensis mexicana) became extinct in Texas, U.S.A., during the 1960s and reintroduction efforts have resulted in an extant population of about 300 free-ranging animals. We studied diet preferences of reintroduced desert bighorn sheep in three mountain ranges in western Texas, U.S.A., during 1994-1995. We predicted that botanical composition and species richness of diets of reintroduced male and female desert bighorns differ when sexes are segregated, but are similar during portions of the year when sexes are aggregated. There were few consistent differences in diet composition between sexes. Species richness of diets of male bighorns was greater than for females. Forbs were highly preferred by both sexes but forb biomass was less than 1 kg ha (-1) in all seasons. Drought and impacts of historical livestock grazing on vegetation may have masked diet partitioning by sex. (C) 2001 Academic Press.