In this open clinical trial conducted in 10 veterinary practices, Ginkgo leaf extract was administered as a dietary supplement to 42 elderly dogs (mean age 11.4 years) at a daily dose of 40 mg/ 10 kg body weight for 8 weeks. The "severity of the geriatric condition" in dogs with a history of geriatric behavioural disturbances (mean duration 12 months), was significantly reduced after 8 weeks of treatment (P = 0.0002). The positive effect was already apparent after 4 weeks. Thirty-six % of the dogs were completely free of clinical signs at study end. Overall efficacy of treatment as judged by the investigator was good or very good in 79% of the dogs. Five of six clinical sign scores (disorientation, sleep/activity changes, behavioural changes, general behaviour and general physical condition/vitality) also showed a significant decrease over the treatment period. In conclusion, these findings provide promising results that could increase the quality of life in the elderly dog and, as a consequence, that of the pet owner. The Ginkgo leaf extract appears to be an efficacious agent that provides a safe dietary supplement for the elderly dog with age-related behavioural disturbances.