Study published in Australian and New Zealand Journal of Public Health, Vol. 34 Issue 2, Pages 160 - 164 (April 2010). The study concluded that "Circumcision appears to have minimal protective effects on sexual health in Australia." Translated into English, "Circumcised men do not have any additional protection against sexually transmitted diseases."
Results: More than half the men (58%) were circumcised. Circumcision was less common (33%) among men under 30 and more common (66%) among those born in Australia. After adjustment for age and number of partners, circumcision was unrelated to STI history except for non-specific urethritis (higher among circumcised men, OR=2.11, p<0.001) and penile candidiasis (lower among circumcised men, OR=0.49, p<0.001).
Circumcision was unrelated to any of the sexual difficulties we asked about (after adjusting for age) except that circumcised men were somewhat less likely to have worried during sex about whether their bodies looked unattractive (OR=0.77, p=0.04). No association between lack of circumcision and erection difficulties was detected. After correction for age, circumcised men were somewhat more likely to have masturbated alone in the previous 12 months (OR=1.20, p=0.02).