To assess the incidence of infusion reactions in patients with rheumatoid arthritis (RA) receiving infliximab treatment with and without betamethasone premedication. To determine whether patients with an atopic diathesis had a better response to corticosteroid pretreatment than those without, and the course of patients' functional capacity and quality of life. A prospective, multicentre, randomised, double blind phase 4 study of 355 patients with RA in two groups: group A received betamethasone and group B placebo, before a 36 week infusion treatment with infliximab. Incidence and severity of infusion reactions from infliximab treatment were assessed. The incidence of reactions to infliximab infusion was <5%. More infusion reactions occurred with betamethasone pretreatment than with placebo. Response to infliximab of patients with atopic backgrounds did not differ in the presence or absence of betamethasone from that of non-atopic patients. Mean Health Assessment Questionnaire score improved by 47% at week 24, quality of life assessed by Short Form-36 improved in mental and physical component subscales. Incidence of infusion reactions with infliximab was low and their severity generally mild, but betamethasone pretreatment did not decrease the incidence and severity of infusion reactions. Betamethasone, therefore, is not recommended as a systematic prophylactic measure, even in atopic patients.