Suicide is an important public health problem for which we have an inadequate public health database. In the United States, decisions about whether deaths are listed as suicides on death certificates are usually made by a coroner or medical examiner. These certification decisions are frequently marked by a lack of consistency and clarity, and laws and procedures for guiding these decisions vary from state to state and even from county to county. Without explicit criteria to aid in this decision making, coroners or medical examiners may be more susceptible to pressures from families or communities not to certify specific deaths as suicide. In addition, coroners or medical examiners may certify similar deaths differently at different times. The degree to which suicides may be underreported or misclassified is unknown. This makes it impossible to estimate accurately the number of deaths by suicide, to identify risk factors, or to plan and evaluate preventive interventions. To remedy these problems, a working group representing coroners, medical examiners, statisticians, and public health agencies developed operational criteria to assist in the determination of suicide. These criteria are based on a definition of suicide as "death arising from an act inflicted upon oneself with the intent to kill oneself." The purpose of these criteria is to improve the validity and reliability of suicide statistics by: (1) promoting consistent and uniform classifications; (2) making the criteria for decision making in death certification explicit; (3) increasing the amount of information used in decision making; (4) aiding certifiers in exercising their professional judgment; and (5) establishing common standards of practice for the determination of suicide.