Background Structured exercise has an important role in mitigating the extensive side effects caused by ongoing prostate cancer treatments, specifically androgen deprivation therapy (ADT) and radiation therapy (RT). Little is known about men's experiences of, and preferences for, structured exercise programmes during active cancer treatment. This study aimed to inform the acceptability of a 6-month supervised intervention that emphasised increasing and varied intensities of aerobic and resistance exercise, by exploring the experiences of men who participated.Methods Individual semi-structured interviews were conducted with an interviewer independent of the exercise study and data was analysed using a descriptive qualitative design.