This WHO collaborative project is the first phase of a programme of work aimed at developing techniques for early identification and treatment of persons with hazardous and harmful alcohol consumption. The aim of the present study was to determine the prevalence of hazardous and harmful alcohol use among patients attending primary health care facilities in several countries, and to examine the correlates of drinking behaviour and alcohol-related problems in these culturally diverse populations. The broader purpose was to determine whether there was justification for developing alcohol screening instruments for cross-national use. One thousand, eight hundred and eighty-eight subjects in Australia, Bulgaria, Kenya, Mexico, Norway and the USA underwent a comprehensive assessment of their medical history, alcohol intake, drinking practices, and any physical or psychosocial problems related to alcohol. After non-drinkers and known alcoholics had been excluded, 18% of subjects had a hazardous level of alcohol intake and 23% had experienced at least one alcohol-related problem in the previous year. Intrascale reliability coefficients were uniformly high for the drinking behaviour (dependence) and adverse psychological reactions scales, and moderately high for the alcohol-related problems scales. There were strong correlations between the various alcohol-specific scales, and between these scales and measures of alcohol intake. Although the prevalence of hazardous and harmful alcohol consumption varied from country to country, there was a high degree of commonality in the structure and correlates of drinking behaviour and alcohol-related problems. These findings strengthen the case for developing international screening instruments for hazardous and harmful alcohol consumption.