Travellers' diarrhoea (TD) is a condition affecting a large number of persons going to Africa, Asia or Latin America. The aetiology varies but is dominated by bacterial enteropathogens. Clinically TD is a self-limiting disease but a considerable proportion of those afflicted become incapacitated for one day or longer. Antibiotic prophylaxis of TD has been proven to be effective in trials comparing doxycycline, trimethoprim, co-trimoxazole, mecillinam, ciprofloxacin or norfloxacin to placebo. With all of those except ciprofloxacin and norfloxacin, selection of resistant Enterobacteriaceae in the faecal flora has been a major problem. In addition, co-trimoxazole has been found to cause high frequencies of adverse reactions. It is quite clear that, to avoid overuse of antibiotics and unnecessary side effects, prophylaxis of TD must be restricted to risk groups, e.g. patients with immunodeficiencies, reduced gastric acidity, inflammatory bowel diseases or serious diseases which may be worsened by TD. In other individuals going to areas with high incidences of TD short-term self-treatment seems to be a better alternative to prophylaxis. Both for prophylaxis and self-treatment, a fluoroquinolone with documented activity against TD seems to be well advised.