The HCR-20 is widely used to assess risk of violence among patients with schizophrenia. Further understanding of the accuracy and changes over time in C and R scores is needed. Using prospectively collected data on 248 men with schizophrenia, the present study found that the HCR-20 significantly predicted aggressive behavior over 24 months. The H, C, R, HCR-20 total, and final risk judgment scores were unable to predict aggressive behavior better than chance among the general psychiatric patients in the first six months after discharge. Changes in three C items, the total R score, and in three R items significantly predicted changes in aggressive behavior.