Clinical trials with ofloxacin have shown that adverse drug events (ADEs) occurred in between 2·43% (Phase II) and 3·1–7–3% (Phase IV) of patients treated and were mostly mild. As with any other drug the true spectrum of rare events can only be fully appreciated after marketing. Since the launch of ofloxacin in June 1985 about 3·5 million patients have been treated in Germany, calculated on the basis of a mean daily dose of 400 mg ofloxacin and a mean duration of treatment of seven days. During these 2·5 years 985 spontaneous national reports of ADEs have been obtained and include rare adverse events (e.g. hallucination, psychotic reaction and shock), not seen in clinical trials The present status of results from postmarketing surveillance is shown and discussed. The favourable overall risk : benefit ratio of ofloxacin appears unchanged.