METHODS: Our index cases were 602 sexually active HIV-positive haemophiliacs (aged 18 years or more) enrolled in the Italian Registry of Haemophilia. Data on the demographic and clinical status of the haemophiliacs, whether their partners had undergone HIV testing, and the results of these tests were collected. RESULTS: To date, 205 (34.1%) partners of HIV-positive haemophiliacs have been tested for HIV, of whom 27 (13.2%) were seropositive. On univariate analysis, haemophiliacs who were unmarried, younger, and asymptomatic were less likely to have partners who had been tested for HIV (P << 0.001). On multivariate analysis, unmarried status [odds ratio (OR), 8.4; 95% confidence interval (CI), 5.4-13.1; P << 0.001] and younger age (OR, 1.9; 95% CI, 1.1-3.2) again predicted a higher rate of non-tested partners. There was no association between the demographic and medical characteristics of HIV-seropositive haemophiliacs and the risk of HIV positivity among their sexual partners. CONCLUSION: This study demonstrates that a high proportion of sexual partners of HIV-positive haemophiliacs have not yet been tested for HIV. The single most important predictor of not being tested was the marital status of the index case. These results emphasize the need to strengthen prevention programmes aimed at minimizing the risk of heterosexual HIV transmission, particularly among younger unmarried haemophiliacs