Background:- This randomised controlled trial (RCT) aims to evaluate the effectiveness of a guided self-help cognitive behavioural intervention to alleviate problematic hot flushes (HF) and night sweats (NS) in men who are undergoing prostate cancer treatment. The trial and the self-help materials have been adapted from a previous RCT, which showed that a cognitive behavioural intervention reduced the self-reported problem-rating of hot flushes in women with menopausal symptoms, and in women undergoing breast cancer treatment. We hypothesize that guided self-help will be more effective than usual care in reducing HF/NS problem-rating at post treatment assessment. Methods/Design:- Seventy men who are undergoing treatment for prostate cancer and who have been experiencing more than ten HF/NS weekly for over a month are recruited into the trial from urology clinics in London. They are randomly allocated to either a four-week self-help cognitive behavioural therapy (CBT) treatment or to their usual care (control group). The treatment includes information and discussion about hot flushes and night sweats in the context of prostate cancer, monitoring and modifying precipitants, relaxation and paced respiration, stress management, cognitive therapy for unhelpful thoughts and beliefs, managing sleep and night sweats, and advice on maintaining these changes.Prior to randomisation, men attend a clinical interview, undergo 24-48-hour sternal skin conductance monitoring, and complete pre-treatment questionnaires (e.g., problem-rating and frequency of hot flushes and night sweats; quality of life; mood; hot flush beliefs and behaviours). Post-treatment measures (sternal skin conductance and the above questionnaires) are collected four-six weeks later, and again at a six-month follow-up. Discussion:- MANCAN is the first randomised controlled trial of cognitive behavioural therapy for HF/NS for men that measures both self-reported and physiologically indexed symptoms. The results will inform future clinical practice by evaluating an evidence-based, non-medical treatment, which can be delivered by trained health professionals. Trial registration:- UK Clinical Research Network UKCRN10904.