ETCG液を基本液とし, これにカフェインまたはテオフィリンを, 実験1では終末濃度0,10,20,30,40mM, 実験2では0,5,10,15,20mMとなるように添加した後, それぞれの液で豚精液を3倍に稀釈し, 5℃で1∿5日間保存試験を行い, 保存日数の経過に伴う精子活力, 活力回復時間, pH, アクロゾーム形態の変化について比較検討を行った。その結果, 全般的には保存日数の経過に伴いアナビオーシスからの回復が遅れる傾向が認められたが, カフェイン, テオフィリン添加区では無添加区に比べて明らかに高い活力を維持し, 活力の回復も早く, pHの低下も認められなかった。また添加区相互の間では, 5∿20mMの低濃度区の方が活力の回復が早く, 30∿40mMと濃度が高くなるにつれてアナビオーシスからの回復が遅れるが, 35℃で長時間高い活力を維持する傾向が認められた。さらにアクロゾームの形態変化に及ぼす影響を併せ考慮すると, 本実験におけるカフェイン, テオフィリン添加の適濃度は10∿15mMであると考えられる。The effects of caffeine and theophylline on the motility and on the acrosome morphology of boar spermatozoa stored at 5℃ were studied. Aliquot of semen were diluted at 30℃ with two volumes of ETCG diluents containing 10,20,30,40mM caffeine or theophylline in Experiment 1,and with those cnotaining 5,10,15,20mM caffeine or theophylline in Experiment 2. Diluted samples were gradually cooled to 5℃. After storage of the sample for 1-5 days at 5℃, sperm motility from anabiosis by incubation at 35℃ and acrosome morphology were assessed. Caffeine and theophylline improved sperm motility markedly during storage at 5℃ and shortened the recovery time from anabiosis. In these experimental conditions, 5-20mM caffeine and theophylline recovered motility sooner, while 30-40mM caffeine and theophylline took more time for recovery but maintained high motility longer. On the contrary, addition of caffeine and theophylline seemed to increase acrosome deterioration slightly. The addition of 10-15mM caffeine and theophylline seemed to be most effective in these experimental conditions