Surrogate endpoints frequently substitute for rare outcomes in research. The ability to learn about completed suicides by investigating more readily available & proximate outcomes, such as suicide attempts, has obvious appeal. However, concerns with surrogates from the statistical science perspective exist, & mounting evidence from psychometric, neurochemical, genetic, & neuroimaging studies suggests that surrogates may be particularly problematic in suicide research. The need for greater phenotypic refinement of suicide-related behaviours, development of & adherence to a shared suicide nomenclature, & conservative interpretation of investigational results that are limited to the precise population & suicide-related behaviour under examination are discussed. (25 refs.) JA