Haemophilus influenzae strains isolated from clinical specimens by the Royal Hospital Microbiology Laboratory and Sultan Qaboos University Hospital Microbiology Laboratory in Oman, between September 1990 and September 1991, were analysed for their susceptibility to ampicillin, chloramphenicol and cotrimoxazole. Of 577 strains 191 (33.01 %) were resistant to ampicillin; of 503, 106 (20.83%) were resistant to cotrimoxazole, and of 277, 13 (5.68%) were resistant to chloramphenicol.