This study was conducted at the La Raya Research Station of IVITA (15° South latitude and 71° West longitude, 4250 m elevation) with 50 alpacas and 20 llamas, 3 to 8 y of age and having at least one previous pregnancy. The alpacas were bred to fertile males for 20 min twice in the same day. The llamas were selected at random from a flock bred to fertile males for 32 d. Accuracy of the following three methods of pregnancy diagnosis were compared: ultrasound, palpation per rectum, and estrous behaviour using teaser males. The same animals were used to test all three methods. Using teaser males with alpacas 84 and 88% accurate diagnoses were obtained at 70 and 125 d of pregnancy, respectively. With llamas, 85 and 95% accuracy was obtained at 75 and 125 d of pregnancy, respectively. Using the ultrasound method, the accuracy of pregnancy diagnosis was 92 and 100% at 80 and 75 d of gestation in alpacas and llamas, respectively. This rate of accuracy fell to 60% as the stage of pregnancy advanced in both species. When palpation per rectum was performed, 100% of pregnancies were diagnosed accurately. In alpacas, palpation was statistically more accurate (P < 0.05) than the ultrasound and estrous behaviour methods, which failed to differ statistically. In llamas, no differences were found among the three methods. No statistical differences (P > 0.05) were found among animal species in any one of the methods tested. © 1990.