Semen stored in a laboratory in Sydney has been defrosted and successfully used to impregnate 34 Merino ewes, with the resulting live birth rate as high sperm frozen for just 12 months.The authors believe the sperm used is the oldest viable stored semen of any species in the world and definitely the oldest sperm used to produce offspring. The original semen samples were donated from sires owned by the Walker family. Those samples, frozen in 1968 by Dr Steven Salamon, came from four rams, including 'Sir Freddie' born in 1963, owned by the Walkers on their then property at Ledgworth. The Walkers now run 8000 sheep at 'Woolaroo', at Yass Plains, and maintain a close and proud relationship with the animal breeding program at the University of Sydney.