Lymphoedema is a significant health problem for some groups of patients and few health authorities have carried out a systematic health needs assessment for this client group. When planning and developing services, there is a need to demonstrate a knowledge of the literature relating to the incidence and prevalence of this condition. To facilitate interpretation of the literature, clarification of the difference between incidence and prevalence rates is included in this review. It is important that the differences between these rates is clearly understood when considering the nature of a chronic, progressive condition. The problems inherent in comparing results from studies which use different definitions of what constitutes 'lymphoedema', as well as different methods of measurement are acknowledged. A number of studies are examined and using information from this review, it is suggested that the prevalence rate of lymphoedema in women treated for breast cancer is in the region of 25-28%. Factors which influence the development of lymphoedema, and the controversy concerning axillary node sampling and dissection are discussed. The need to consider patients with lymphoedema due to very advanced cancer, and those with lower limb problems is also highlighted.