The study was carried out with the objective to evaluate the influence of season (summer and winter) on seminal characteristics of alpacas. Forty semen samples, 20 for each season, were collected from 4 adult alpaca by artificial vagina technique and evaluated immediately after collection to determine the following semen characteristics: (a) volume, (b) pH, (c) viscosity, (d) color, (e) concentration, (f) motility, (g) viability, (h) abnormalities, and (i) HOST test. Statistical analyses of data were made with least square ANOVA. The males were fed the same diet during both seasons and collection time was standardized in 10 min. The results obtained present differences in viscosity (5.9 ± 0.4 v. 3.7 ± 0.7 mm), motility (58.8 ± 22.1 v. 77.3 ± 11.6%), and concentration (135.9 ± 88.7 × 10⁶v. 242.4 ± 140.9 × 10⁶; P < 0,05) but not in volume (1.9 ± 0.8 v. 2.1 ± 0.8 mL), pH (7.01 ± 0.3 v. 7.1 ± 0.3), viability (52.9 ± 18.4 v. 64.5 ± 15.9%), HOST test (56.1 ± 15.8 v. 49.3 ± 13.2%), and abnormalities (82.5 ± 7.2 v. 88.1 ± 7.0%) for the summer and winter seasons, respectively. The results suggest differences for some characteristics and possible differences in the scrotal thermoregulation of the alpacas with respect to others species.