Some amino acids can protect mammalian sperm cells against oxidation during thermal stress caused by freezing/thawing. Thus, the objective was to evaluate the protective action of the association of the amino acids L-proline (Pro) and L-glutamine (Glu) against the cryoinjury caused to sheep sperm after cryopreservation. Eight ejaculates were collected from four sheep (n=32) and diluted in Tris-Egg Yolk-Glycerol until the final concentration of 200 x10 6 sptz/mL and kept in a water bath at 32 °C. The amino acids were added as follows: control (without adding amino acids), Pro+Glu 1 (100 μM Pro + 500 μM Glu), Pro+Glu 2 (300 μM Pro + 1000 μM Glu), Pro+Glu 3 (500 μM Pro + 1500 μM Glu) and Pro+Glu 4 (700 μM Pro + 2000 μM Glu). Afterwards, the semen was cooled to 5 °C for 2 h, after that period, filled in 0.5 mL straws and then placed under liquid nitrogen vapor (N 2 L), 8 cm from the liquid sheet for 15 min, and then immersed on the N 2 L. The samples were analyzed for sperm motility, plasma membrane and acrosomal membrane integrity, mitochondrial activity and binding test. The variables were subjected to the normality tests (Lilliefors test) and homoscedasticity tests (Cochran and Bartlett test), afterwards the variables of normal distribution were subjected to analysis of variance and the means compared by the Tukey test with a significance level of 5%. The Pro+Glu 3 group exhibited sperm with a greater (P<0.05) motility after thawing. In addition, the highest percentage of plasma and acrosomal membrane integrity were obtained using Pro+Glu 1, Pro+Glu 2 and Pro+Glu 3; and Pro+Glu 2 and Pro+Glu 3, respectively. Amino acids also kept mitochondrial activity high compared to the control, with Pro+Glu 3 resulting in greater activity (P<0.05). Sperm viability was higher (P<0.05) with the use of Pro+Glu 2 and Pro+Glu 3 than in the control. The number of sperm that showed the ability to bind to the egg yolk perivitelline membrane was higher (P<0.05) in semen treated with amino acids. It is concluded that the addition of synthetic amino acids in the semen of sheep before cryopreservation improves sperm quality and fertilization potential and can thus be added in cryopreservation protocols.