The prenatal development of the alpaca was studied. An evaluation of the reproductive tract by rectal palpation was described throughout pregnancy. Forty-eight embryos/fetuses were collected from a similar number of pregnant females at La Raya research station, in Cusco, Peru. Fetal data were analyzed by least squares regression. Ninety-eight percent of fetuses were located in the left uterine horn; however, corpora lutea were distributed evenly between the left and right ovaries. The pregnant uterus was within the pelvic cavity until 90 days of pregnancy, thereafter, the uterus was located cranial to the brim of the pelvis within the abdominal cavity. The growth curves of body weight, crown-rump length, vertebral column length, curved crown-rump length were quadratic in nature. The sex of the fetus could be distinguished at 60 days. Hair was present on the lips, eyebrows and tail at 210 days. The body was completely covered by fiber by 240 days of gestation. The mammary gland began to increase in weight only 30 days prior to parturition. © 1993.