A multiple dose trial of BMY-28100, a new oral cephalosporin, was performed in volunteers, in order to evaluate its safety and pharmacokinetics. BMY-28100 was administered orally 250 mg t.i.d. for 7 days to seven healthy adult males. No side effects nor abnormal laboratory findings were observed. Peak levels of serum concentration and half-lives after the first and 19th administrations were 4.45 and 4.83 micrograms/ml and 1.3 and 1.1 hours, respectively. Urinary recoveries in 24 hours were 53.4% on day 1 and 56.2% on day 7. There was no tendency towards accumulation in blood upon continuous daily dosing of 250 mg t.i.d.