Psychological tests are being used increasingly in dialysis populations, both for psychosomatic research and for clinical evaluations, warranting careful examination of their uses and limitations. Characteristics associated with dialysis populations can limit the validity of many psychological tests which are useful in other populations. These characteristics include such factors as the great biological heterogeneity of dialysis patients, their uniquely dependent relationship to treating staff, and their tendency to respond with socially desirable answers. There is a need to develop psychological tests that are specific for dialysis populations and take into account social desirability response bias. At present, the limitations of psychological tests in a dialysis population are substantial.