Patient compliance with respect to a liquid antacid (Novaluzid) was examined in an open multicentre study. The study included 186 patients with various upper gastrointestinal conditions. The patients were randomly assigned to either 2 or 4 weeks' treatment with 10 ml Novaluzid 1 and 3 hours after each meal and at bedtime. They were not informed that they were taking part in a study. The compliance was high, with no difference between the two groups; 82% and 79%, respectively, and showed no dependency on patient age, diagnosis or previous use of antacids.