The morphologic appearance of the ovaries, uterus, and cervix of nonpregnant and pregnant (less than 50 days) llamas (n = 21) were monitored daily by transrectal ultrasonography, and uterine tone was monitored by transrectal digital palpation. Follicle size and the presence or absence of corpora lutea were recorded and related to changes in morphology of uterus and cervix. Emphasis was given to the dynamics of curling of uterine horns and changes in uterine tone. For statistical purposes, uterine and cervical characteristics were scored 1 to 4 (minimal to maximal). Data were placed into 1 of the following reproductive statuses: 1) follicular dominance, 2) luteal dominance, and 3) pregnancy. Follicles were characteristically arranged along the periphery of the ovary, and large follicles and the corpus luteum protruded distinctly from the ovarian surface. The preovulatory follicle grew at a mean rate of 0.7 mm/day and the average diameter on the day before ovulation was 10.6 +/- 0.9 mm. Ovulation (Day 0) was detected an average of 1.8 days after a single mating. The mature corpus luteum was 11-13 mm in diameter and was characteristically hypoechogenic with a white (echogenic) horizontal area in the center. Pregnancy was detected as early as 11 days post-mating and all (7/7) singleton embryonic vesicles were detected in the left uterine horn. Uterine and cervical echotexture was darker (p less than 0.01) during follicular dominance than during luteal dominance and pregnancy, indicating a decrease in tissue interfaces or an increase in intercellular fluid during follicular dominance. The cervical folds became echogenic and prominent during luteal dominance.(ABSTRACT TRUNCATED AT 250 WORDS)