OBJECTIVE--To investigate the intrinsic effects of individually prescribed homoeopathic medicines. DESIGN--Randomised double blind placebo controlled study. SETTING--Paediatric outpatient department of university hospital. PATIENTS--175 children with frequently recurring upper respiratory tract infections. Of the 170 children evaluable, 86 were randomised to homoeopathic medicines (47 boys, 39 girls; median age at start 4.2 years; median number of episodes in past year 4) and 84 to placebo (43 boys, 41 girls; median age at start 3.6 years; median number of episodes in past year 4). MAIN OUTCOME MEASURES--Mean score for daily symptoms, number of antibiotic courses, and number of adenoidectomies and tonsillectomies over one year of follow up. RESULTS--The mean daily symptom score was 2.61 in the placebo group and 2.21 in the treatment group (difference 0.41; 95% confidence interval -0.02 to 0.83). In both groups the use of antibiotics was greatly reduced compared with that in the year before entering the trial (from 73 to 33 in the treatment group and from 69 to 43 in the placebo group). The proportion of children in the treatment group having adenoidectomies was lower in the treatment group (16%, 8/50) than in the placebo group (21%, 9/42). The proportion having tonsillectomies was the same in both groups (5%). CONCLUSION--Individually prescribed homoeopathic medicines seem to add little to careful counselling of children with recurrent upper respiratory tract infection in reducing the daily burden of symptoms, use of antibiotics, and need for adenoidectomy and tonsillectomy.