Lower cancer mortality has been reported among hospitalized psychiatric patients, especially schizophrenics, than in the general population. This has been attributed by some to a protection afforded by the psychiatric disease itself or to medication far it. We would like to suggegst that known factors associated with lower cancer mortality are probably responsible. These factors in clude inaccuracies of cancer and psychiatric diagnoses, length of hospitalization, errors of statistical method such as ignoring competing risk, and environmental effects during hospitalization such as curtailed smoking and hospital diet.