1. A controlled clinical trial was conducted to assess the effectiveness of a homoeopathic preparation in the treatment of influenza‐like syndromes. 2. 237 cases received the test drug and 241 were assigned to placebo. Patients recorded their rectal temperature twice a day, and the presence or absence of five cardinal symptoms (headache, stiffness, lumbar and articular pain, shivers) along with cough, coryza and fatigue. 3. Recovery was defined as a rectal temperature less than 37.5 degrees C and complete resolution of the five cardinal symptoms. 4. The proportion of cases who recovered within 48 h of treatment was greater among the active drug group than among the placebo group (17.1% against 10.3%, P = 0.03). 5. The result cannot be explained given our present state of knowledge, but it calls for further rigorously designed clinical studies.