Experiments were carried out to study the effect of two techniques of deep-freezing semen (P stands for Pellets and M stands for Maxi-straws). Ejaculates were obtained from 5 Alentejano swine breed boars and 2 contrast boars (1 Duroc x LW and 1 LW). Regarding P-method, semen drops were previously frozen (on a carbonic ice plate at, -76 degreesC), before being deep-frozen into liquid nitrogen (Paquignon et al., 1974). As far as the M-method was concerned, it was adapted from Westendorf et al. (1975), using a programmable freezing chamber. Concerning in vitro sperm evaluation, pellets were placed directly into four different thawing solutions at 42 degrees C (SD-glucose-sodium citrate solution, BTS, MR-A, SD plus BTS) and maxi-straws were thawed for 40s in, a water bath at 40 degrees C. After thawing was completed, semen of the later method was also diluted into the same four solutions previously mentioned. During evaluation procedures, diluted semen was maintained at 37 degrees C.