The Australian Gonococcal Surveillance Programme monitors the antibiotic susceptibility of Neisseria gonorrhoeae isolated in all States and Territories. In 2005 the in vitro susceptibility of 3,886 isolates of gonococci from public and private sector sources was determined by standardised methods. Different antibiotic susceptibility patterns were again seen in the various jurisdictions and regions. Resistance to the penicillins nationally was 29.5 per cent and, with the exception of the Northern Territory, ranged between 14 and 47 per cent. Quinolone resistance in gonococci increased with resistance to this agent found in all jurisdictions and in a larger proportion of strains and with higher minimal inhibitory concentrations (MICs). Nationally, 30.6 per cent of all isolates were ciprofloxacin-resistant and most of this resistance was at high MIC levels. All isolates remained sensitive to spectinomycin. Slightly more than one per cent of isolates showed some decreased susceptibility to ceftriaxone (MIC 0.06 mg/L or more). A high proportion of gonococci examined in larger urban centres were from male patients and rectal and pharyngeal isolates were common. In other centres and in rural Australia the male to female ratio of cases was lower, and most isolates were from the genital tract.