The study was conducted through a questionnaire sent to all agencies of the International Criminal Police Organization in participating countries. Information was requested for the years 1970-1977 and covered the numbers of police officers killed, total population, and total number of officers. Rates of police officer murders were then correlated with other information, such as the country's number of police per capita, 1971-1975 general homicide and suicide rates, police prestige, and per capita GNP. Results show widely defferent rates of police officer murders, from 22 per 100,000 population in the United States to 1.36 per 100,000 in England and 1.76 per 100,000 in Japan. Moreover, the American rate was significantly higher than that for Canada, the next highest with 9.31 per 100,000 population. Although the police officer murder rate correlated significantly with large population, high general homicide rate, and high GNP, it bore no relation to the suicide rate, police prestige, or number of police per capita. A comparison of police officer murders in Canada and United States discusses general homicide rates, types of incidents yielding the greatest numbers of police officer murders, and characteristics of suspects. Tables, seven references, and a note are included.