Background Sexual risk behaviour increased since the introduction of antiretroviral treatment against HIV-1. Consequently, since the mid-90s the gonorrhoea transmission was raised posing a serious public health problem especially among men who have sex with men (MSM). We examined if separate sexual networks exist of HIV-infected and of HIV-negative MSM in relation to transmission of gonorrhoea. Using molecular typing of Neisseria gonorrhoeae (NG) we aimed to identify clusters of patients with specific NG strains and examined possible linkage to HIV infection and other characteristics. Methods From July 2008 to August 2009, MSM visiting the Amsterdam outpatient clinic were recruited for a network study concerning sexually transmitted infections (STI). Inclusion criteria were age ≥18&emsp14;years, homosexual contact in the preceding 6&emsp14;months, and giving informed consent. After screening for STI the participants answered questions regarding sexual behaviour, meeting places, and characteristics of sexual partners (up to 4 sex partners). Only patients with an anal or genital NG infection (n=246) were included in the current analysis. NG cultures were amplified and genotyped using a published NG-MLVA typing method. Results Included patients (median age 36&emsp14;years, IQR 30−42) were predominantly Dutch (83%). Coinfections with chlamydia (28%) and HIV (48%) were common. Hierarchical cluster analysis of 246 MLVA profiles classified 152/246 MSM in 13 large clusters (5 to 36 patients) indicating the circulation and ongoing transmission of different NG strains in this population. In three clusters a significantly (p<0.001) higher proportion of NG isolates had decreased susceptibility to cefotaxime. HIV infected MSM were older than HIV negative MSM and were evenly distributed over the NG clusters (see <cross-ref type="fig" refid="fig1">Abstract P1-S2.45 figure 1</cross-ref>). There were no significant differences in age, nationality, nor in other coinfections between the various NG ...