SummaryA case of acute renal insufficiency after rifampicin reingestion has been described. This occurred with a patient, who had previous been treated with a long-term daily regimen. The interruption period—i.e. time between the last two ingestions—Was 35 months. Such a long interruption period has hitherto not been reported to our knowledge. Haemodialysis was necessary, and resulted in full recovery. Twelve months later rifampicin-dependent antibodies were still present.Since the introduction of intermittent rifampicin therapy, serious side effects have been reported, such as thrombocytopenia, haemolysis, hepatotoxicity and acute renal failure. More recently, several cases of acute renal insufficiency after a break in a daily treatment have been described. In most cases therapy was interrupted for some days, rarely for months. Antibodies to rifampicin could be found in the cases tested and immune complexes may play an important role in the occurrence of these lesions.It is stressed that intermittent rifampicin treatment and every renewed therapy—even after a long interruption period and whatever the first regimen was (daily or intermittent)—may have serious complications.