Campylobacter jejuni antibiotic resistance is rising with a variable geographical pattern; but there is limited data from the Arabian Gulf region. We assessed the sensitivity of human (117) and chicken (33) C. jejuni isolates to erythromycin, ciprofloxacin, tetracycline and trimethoprim-sulfamethoxazole by agar dilution, disc diffusion and the E test. Only 2 human isolates were resistant to erythromycin. In contrast, over 80% of chicken and human isolates were resistant to ciprofloxacin. A significantly higher proportion of chicken isolates than human isolates were resistant to tetracycline, with much higher MIC(50) values (P < 0.001). The MIC(90) for trimethoprim-sulfamethoxazole by agar dilution was 40 microg/ml. Comparison of the results of the agar dilution method and E test showed 1 major disagreement and 8 minor disagreements for erythromycin, 4 major disagreements for ciprofloxacin and 23 disagreements for tetracycline (19 were major disagreements). This was the first study to describe the pattern of antibiotic resistance in Campylobacter isolates in this region; the results indicate a high degree of erythromycin sensitivity that validates the continued use of this agent as a first-line therapy for Campylobacter enteritis. These findings have wide implications because of the large, highly mobile expatriate population in this setting. In addition, the correlation between agar dilution and disc diffusion supports the use of the latter as an alternative susceptibility testing method for Campylobacter.