The range of methods now available to estimate body composition is extensive. In most cases there is a relationship between cost, complexity and information content. The consequence is that choices can still be made depending on the finances available and the needs of the health professional. This paper reviews four methods ranging in availability and clinical detail. The alternatives are use of skinfolds, electrical impedance, underwater weighing and dual energy X-ray absorptiometry. These should provide the practitioner with viable options to consider in the assessment of body composition. Although no method has been designed specifically for children, reference is made throughout to studies on paediatric subjects of the major issues involved in these methods, which will assist paediatric endocrinologists in making informed decisions.