A well-known side effect of prostate cancer treatment is erectile dysfunction. However, little is known about how men and their sexual partners think about the threat of erectile dysfunction prior to prostate cancer treatment. Twenty-one patients who had been diagnosed with early prostate cancer, but not yet treated, and 13 female partners of these men were recruited from two urologists' offices. In separate, semistructured individual interviews with men and their partners, thoughts about the threat of erectile dysfunction were solicited. Men's reactions to the possibility of losing their sexual capacity due to prostate cancer-related treatment were linked to their current level of sexual function. Women reacted to erectile dysfunction by stressing the existence of other relationship dimensions, whereas they were aware about the gravity of their male partners' feelings about potency. Finally, both men and women alike had concerns about the implications of erectile dysfunction on their relationship. Physicians advising men about treatment options should consider exploring men's current sexual function, thoughts about identity, and especially men's relationship situation. Physicians addressing these issues with men and their partners should provide resources for counseling.