Respiratory and otitis isolates of 807 Streptococcus pneumoniae, 816 Haemophilus influenzae and 446 Moraxella catarrhalis were collected from 21 clinical microbiology laboratories for antimicrobial susceptibility testing in 1995. After a period of relative stability in 1981 and 1987-1990, beta-lactamase production increased in H. influenzae. Among middle ear isolates from children under 6 years, beta-lactamase production increased from 8% to 24% in H. influenzae and from 81% to 96% in M. catarrhalis since the survey in 1987-1990. 1.2% of S. pneumoniae were penicillin-resistant and 4.2% intermediately resistant; 5 years earlier among otitis isolates of children only 1.7% intermediate resistance was found. Ampicillin resistance was seen among 1.9% of non-beta-lactamase-producing strains of H. influenzae. Resistance to trimethoprim-sulphamethoxazole occurred in 9.4% of S. pneumoniae, 7.4% of H. influenzae and 0.7% of M. catarrhalis. Frequencies of azithromycin resistance were 3.0% in S. pneumoniae and 1.6% in H. influenzae, and those of tetracycline resistance were 6.7% in S. pneumoniae and 1.2% in H. influenzae.