A survey was conducted to investigate the incidence and antibiotic resistance of clinical isolates of Gram-negative non-fermentative bacteria, isolated during a one-year period in Italy. Overall, these microorganisms account respectively for 11.47% and 20.5% of all Gram-negative bacteria. The most representative species isolated during the study were: Acinetobacter, Flavobacterium, Alcaligenes, Achromobacter and Xanthomonas species. As regards their antimicrobial pattern of resistance, this survey demonstrated the wide differences existing within each group. The antimicrobial agents usually active against Pseudomonas aeruginosa do not seem to be useful against these microorganisms.