Objective – To evaluate the effects of homoeopathic ultrahigh dilutions of Aconitum napellus in Baker’s yeast-induced fever in rabbits. Methods – Rabbits were divided into 4 groups and each group contained 6 rabbits. Baker’s yeast suspension (20%) was injected subcutaneously. After fever induction, paracetamol and homoeopathic ultrahigh dilutions (A. napellus 200c and 1 000c) were given orally. Rectal temperature was measured with digital thermometer hourly. Results – Fever was induced in all the rabbits after 4 hours of Baker’s yeast administration. A. napellus 200c and 1000c significantly reduced the temperature (P > 0.05). In positive control, temperature decrease was more significant (P > 0.001). Conclusion – The above findings indicate the effectiveness of ultrahigh dilutions of A. napellus in Baker’s yeast-induced fever in rabbits. However, the effects were slower and less significant than standard medicine. Moreover, future research is required to know their mechanism of reducing temperature.