This study sought to discover what proportion of all homicides are committed by people with a serious mental illness, establish any existing trends in this proportional homicide rate, and discern their victims' characteristics. A retrospective study was employed to gather information on all persons committing homicide in New Zealand between 1970 and 2000. This data was obtained from various Governmental datasets, such as the Police Homicide Monitoring database, Ministry of Health records, and the New Zealand Parole Board records of all people convicted of murder. This authors discovered that victims of homicide committed by people with a serious mental illness were more likely to be family members. The results of the study also show that the rate of homicide committed by people with a serious mental illness has reduced as a proportion of total homicides, from 19% in 1970 to 4% in 2000. Therefore, as there is a lower risk of homicide being committed by persons with a serious mental illness, the authors question the widespread public perception that mental health services are not protecting society from harm. The authors suggest that the media plays a significant role in influencing and exacerbating negative and misleading images of persons with a serious mental illness. Implications and recommendations for policy and future research in the area of mental health are also discussed.