Keeping in mind the overall treatment failure rate of 20.9% with amoxicillin from the MASCOT study (1999 – 2001), it is expected that the proportion of patients who will fail to respond with standard dose amoxicillin will be around 21.0%.7 In order for double dose to be more efficacious there should be a difference of more than 5% in the treatment success rate as compared to the standard dose. The researchers assume that the failure rate will not be more than 13% with double dose amoxicillin. By using the power of 80% and the confidence interval of 95%, the estimated sample size comes to 369 for each group. Assuming the loss to follow up to be 15% (as it is an out patient study and having day 14 follow-up) the estimated sample size will be 425 patients in each group, a total of 850 patients. Thus 900 patients will be enrolled in one and a half ARI season.