INTRODUCTION: Prostate cancer (PCa) treatments are associated with a high incidence of erectile dysfunction (ED). Interventions to help men with iatrogenic ED have largely focused on penile tumescence adequate for vaginal penetration. Less research has been undertaken on sex practices other than penile/vaginal intercourse. AIM: The aim of this study was to explore forms of sexual practice engaged in by men following treatment for PCa. We focused in particular on anal intercourse (AI) as practiced by both nonheterosexual (i.e., gay-identified men and other men who have sex with men) and heterosexual men. We sought to determine how common AI was subsequent to PCa treatment and how flexible AI practitioners were in their modes (e.g., from insertive to receptive) when faced with iatrogenic ED. METHODS: An international online survey was conducted in 2010-2011 of men treated for PCa, where participants (N = 558) were asked explicitly about their sexual practices before and after PCa treatment. MAIN OUTCOME MEASURES: The outcome measures were the numbers and percentages of men who practiced AI before and after PCa treatment as well as the percentage who changed AI practice after PCa treatment. RESULTS: Five hundred twenty-six men (90 nonheterosexual men; 436 heterosexual men) answered questions on AI practices. A proportion of nonheterosexual (47%) and heterosexual men (7%) practiced AI following PCa treatment, and did so in all modes (insertive, receptive, and "versatile"). Many nonheterosexual men continued to be sexually active in the face of iatrogenic ED by shifting from the insertive to receptive modes. A few men, both heterosexual and nonheterosexual, adopted AI for the first time post-PCa treatment. CONCLUSIONS: Flexibility in sexual practice is possible for some men, both nonheterosexual and heterosexual, in the face of iatrogenic ED. Advising PCa patients of the possibilities of sexual strategies that include AI may help them in reestablishing a sex life that is not erection dependent. Dowsett GW, Lyons A, Duncan D, and Wassersug RJ. Flexibility in men's sexual practices in response to iatrogenic erectile dysfunction after prostate cancer treatment. Sex Med 2014;2:115-120.