Boar sperm stored in a commercial extender at 17°C for nine days showed decreased plasma membrane integrity, acrosome integrity, and motility. The eosin-nigrosin method identified the highest percentage of live sperm, while the hypoosmotic swelling test found the lowest. Staining methods showed significant differences in results compared to sperm motility. Plasma membrane integrity correlated positively with each other and with sperm motility but negatively with aspartate aminotransferase activity. The study confirmed that aging boar sperm during liquid preservation led to a loss of function and integrity of the sperm plasma membrane. Tests used in the study can help determine the number of healthy sperm cells during long-term semen preservation.