P. aeruginona infections need accurate antimicrobial susceptibility data, as treatment mainly relies on antibiotic efficiency in debilitated patients. Vitek 2, a popular automated susceptibility testing method, was compared with Etest to assess its reliability on 150 Belgian P. aeruginonas isolates. Vitek 2 and Etest exhibited a high degree of concordance, but some discrepancies in clinical category were evident for cefepime (high minor and borderline very major error rate) and for piperacillin/tazobactam (high very major error rate). Vitek 2 appears to yield valuable information to the clinician concerning the antimicrobials amikacin, ceftazidime, ciprofloxacin and meropenem, in the setting of pseudomonas infection. For cefepime and piperacillin/tazobactam, a confirmatory testing by means of disk diffusion is worth considering.