This study was conducted at the installation of the Rural Academic Unit-Tiahuanaco of the BCU, located in the community of Achaca, third municipal section of Ingavi province, department of La Paz. It is 57 km from the La Paz-Desaguadero international highway, at 68 degrees 42 minutes 28 seconds latitude South by 16 degrees 35 minutes 41 seconds longitude West, at an altitude of 3856 meters above sea level. The study went from October 2000 to September 2001. The study consisted of determining the concentrations of the biochemical components in llama seminal plasma at three ages. Components studied were glucose, inorganic phosphate, creatinine, total protein, albumin, globulins, cholesterol, calcium, potassium, sodium, and magnesium. Twelve male llamas of 3, 4, and 5 years were selected and acquired from the Choquecota area of the Carangas province, department of Oruro. Four animals were chosen at each age and were subjected to a training period of semen collection during 2 months, using the artificial hindquarters designed for this effect. The 6 that best responded to the training were used for the investigation. Eight collections were obtained from each animal over the course of the study, and they were used for laboratory analysis. The results were analyzed using a hierarchical factorial design that involved a mixed analysis (nested and crossed) of the factors of age and collections. (The averages of two collections corresponding to each week were analyzed.) Each weekly collection average per age was an experimental unit. Four experimental units were obtained for each age, and the analysis of the data was done with the SAS statistics package version 6.12. From the analyses done the following results were obtained: the concentrations of glucose (6.246 [plus or minus] 0.716 mg/dl), creatinine (3.459 [plus or minus] 1.27 mg/dl), cholesterol (67.28 [plus or minus] 18.21 mg/dl), potassium (8.249 [plus or minus] 1.78 mEq/L), and sodium (123.187 [plus or minus] 18.39 mEq/L) did not show significant differences between ages or collections (p>0.05). The concentrations of calcium (12.138 [plus or minus] 3.64 mg/dl) and magnesium (1.943 [plus or minus] 0.52 mEq/L) showed significant (p<0.05) differences in age only and not in collections. Globulins (1.574 [plus or minus] 0.51 g/dl) showed differences between collections (p<0.05) but not between ages. Total protein (3.732 [plus or minus] 0.45 g/dl), albumin (2.158 [plus or minus] 0.46 g/dl), and inorganic phosphate (9.42 [plus or minus] 2.42 mg/dl) showed differences both between ages and between collections (p<0.05).