Oxidative stress emerges as a key player in the ageing process. Controlled ozone administration is known to promote an oxidative preconditioning or adaptation to oxidative stress. The present study investigated whether prophylactic ozone administration could interfere with the age-related changes in the heart and the hippocampus of rats. Four groups of rats, aged about 3 months old, were used. Group 1 (Prophylactic ozone group) received ozone/oxygen mixture by rectal insufflations (0.6 mg/kg) twice/week for the first 3 months, then once/week till the age of 15 months. Group 2 (Oxygen group) received oxygen as vehicle for ozone in a manner similar to group 1. Group 3 (Aged control group) was kept without any treatment until the age of 15 months. A fourth group of rats (Adult control group) was evaluated at 3 months of age to provide baseline data. Ozone alleviated age-associated redox state imbalance as evidenced by reduction of lipid and protein oxidation markers, lessening of lipofuscin deposition, restoration of glutathione levels in both tissues and normalization of glutathione peroxidase activity in the heart tissue. Ozone also mitigated age-associated energy failure in the heart and the hippocampus, improved cardiac cytosolic Ca2+ homeostasis and restored the attenuated Na+, K+-ATPase activity in the hippocampus of aged rats. These data provide new evidence concerning the anti-ageing potential of prophylactic ozone administration. Copyright © 2012 John Wiley & Sons, Ltd.