A survey of antibiotic sale behaviour in retail chemist shops in Nairobi revealed that about 64% of chemists sell antibiotics without prescriptions from doctors. Most shops sold underdose drugs according to the request of the patient. The practice is more common in peri-urban than city centre chemists. Out of the 128 chemist shops visited, 82 sold the antibiotic, 33 sent the patients to go and see the doctors while 13 did both. Sixty eight per cent of the chemists in the city centre recommended the taking of full antibiotic course to the patients while only 46% in peri-urban centres did so. Even after the recommendation, some of the chemists still sold under dose drugs. Some of the drugs were sold in envelopes without any instruction at all and none of the drugs sold were fully labelled. Only seven chemists sold septrin, the brand of co-trimoxazole requested by the patients, the rest sold various brands of the drug some of whom still labelled the brands 'septrin'.