The ovaries of 74 llamas were examined daily by transrectal ultrasonography for at least 30 d. Hemorrhagic follicles were observed in 13 (18%) llamas (incidence per anovulatory dominant follicle, 16%). The proportion of llamas in which a hemorrhagic follicle was detected was different among groups (nonmated, 8 25; mated to a vasectomized male, 4 21; mated to an intact male, nonpregnant, 1 10; mated to an intact male, pregnant, 0 18; P<0.05). A hemorrhagic follicle, observed grossly after ovariectomy, was large (13 mm) and fluctuant, with a thin translucent wall and dark red contents. No ovulatory stigma was detected, and after incising the wall, bloody fluid escaped and the follicle collapsed leaving only a small blood clot within the antrum. Ultrasonically, the formation of a hemorrhagic follicle was indicated by scattered free-floating echogenic spots within the follicular antrum which swirled upon ballottement of the ovary. The antral contents appeared to become organized (did not swirl when ballotted) after follicle growth ceased. Ultrasonic indications of antral hemorrhage were not observed in any follicles in which ovulation was later detected ( 0 45 ovulatory follicles). All of the hemorrhagic follicles ( 13 13) involved the dominant follicle of a wave during which no copulatory stimulus was applied. Hemorrhagic follicles were apparently anovulatory and were repeatable (P<0.05) within individuals. The interval from first detection to the first day of maximum diameter was longer (P<0.05) and maximum diameter was greater (P<0.0001) for hemorrhagic follicles than nonhemorrhagic follicles (16.4 versus 13.1 d and 22.1 versus 12.8 mm, respectively); however, the interwave interval was not affected by the presence of a hemorrhagic follicle. Luteinization of the hemorrhagic follicle was indicated (thickened wall) in two llamas by an elevated plasma progesterone concentration and/or by ultrasound. By their large size, hemorrhagic follicles may be interpreted as hemorrhagic follicular cysts; however, they were not associated with other ovarian irregularities or with infertility. © 1991.