Recent changes in mental health care have necessitated reevaluation of Peplau's nursing theory. There is an expanding body of nursing knowledge and a debate is taking place regarding the difference between models and theories. Peplau's theory considers nursing as an interpersonal process between nurse and patient. The theory lacks empirical investigation and is not yet tested regarding the multidisciplinary team approach, which is largely based on the medical model. For the theory to gain credibility within the dynamics of the multidisciplinary team, it must be tested within a framework of robust research design involving various diagnostic groups and practice settings. Until such time, the theory's utility must seriously be questioned within contemporary mental health practice.