A multi-centre study in general practice was carried out to compare the efficacy of two doses of cephalexin-500 mg or 1 g - given in a twice daily dosage regimen to 752 patients with respiratory or soft tissue infections. After 5-days' treatment, over 80% of the patients were cured or considerably improved, with no differences between the two treatment groups. Considering the lower respiratory and soft tissue infections together, 1 g cephalexin twice daily produced a better clinical response after 48-hours' treatment, suggesting a more rapid response with the higher dosage, but this trend did not reach statistical significance. Twice daily cephalexin therapy was also effective in patients with concurrent illness, and in those patients who had been treated unsuccessfully with other antibacterial therapy in the week prior to trial entry. No drug interactions were reported and the incidence of side-effects was low.