Abstract: Semen preservation is a critical procedure to guarantee that good quality semen is adequate for advanced assisted reproduction. The present study aimed to evaluate viability of Nguni bull spermatozoa diluted with modified Ham=s F10 culture medium stored at different storage conditions (5, 12, 17°C and controlled room temperature 24°C) for 72 h. Following microscopic evaluations, uncontaminated semen samples with progressive motility >70% were pooled before being aliquoted randomly into four test tubes of modified Ham=s F10. Diluted samples were distributed unsystematically to each of the four temperature conditions (5, 12, 17 and 24°C) and stored for 72 h. Computer aided sperm analysis was used to evaluate sperm motility, DNA fragmentation and viability. The highest spermatozoa motility rate (86.5%) and viability (26.5%) was observed with 24°C as compared to the other three temperatures 17°C (69.5; 8.0%), 12°C (50.3; 2.5%) and 5°C (35.1; 0.5%), respectively for 72 h. The overall sperm viability rate of the storage conditions 24, 17, 12 and 5°C<30% after 72 h. There was no significant difference in sperm DNA fragmentation amongst the four storage conditions (p<0.01). In conclusion, motility and viability rate of Nguni spermatozoa extended with modified Ham=s F10 culture medium decreased noticeably regardless of the storage temperature condition.