The social network can be an important pathogenic, pathoplastic, or protective factor in the development and course of mental and somatic illnesses. "Social network" describes a complex construct which has been understood, defined, and operationalized in many different ways. In research and clinical practice it is advisable to refer to scientifically elaborated instruments when measuring or evaluating the social network of patients. In this paper a review is given on available instruments for the measurement of the social network. They are discussed in respect to their clinical usefulness. Only few measures can be recommended for clinical practice because of the time needed to get the information or because of their content.