A single-blind multicentre crossover study was carried out in general practice of 47 patients with symptoms due to hyperacidity. Patients were allocated at random to receive treatment either with Gastrils for the first 2 weeks followed by Aludrox tablets for the second 2 weeks, or with Aludrox tablets for the first 2 weeks followed by Gastrils for the second 2 weeks. Clinical evaluation took place initially, after the first 2 weeks treatment and after the second 2 weeks treatment. The efficacy and acceptability of both preparations were compared, likewise the flavours of different Gastrils packs. Analysis of the results showed that peppermint flavoured Gastrils were significantly preferred to Aludrox tablets, and a peppermint flavour to a banana flavour. Side-effects were significantly more prevalent with Aludrox tablets. Differences in antacid response were similar, but numerically, if not statistically significantly, Gastrils had a more beneficial effect.