In relation to compliance problems it was investigated whether phenoxymethylpenicillin dosed twice or 3 times daily was equally effective in tonsillitis due to beta-haemolytic streptococci group A. In a randomized, controlled and single blind multicentre study 206 patients older than 5 years with a positive culture of group A streptococci were treated with phenoxymethylpenicillin for 7 days. 101 patients received the daily dosage divided in 2 doses and 105 patients divided in 3 doses a day. The cure rate (a combination of bacteriological and clinical cure) was 82.0% in the 2-dosage regimen, and 88.2% in the 3-dosage regimen. The difference was not statistically significant. In conclusion, phenoxymethylpenicillin dosed 2 or 3 times daily seems to be equally effective in tonsillitis due to group A streptococci.