In a national sample of 11,634 Canadians aged 15 years and above, risk curves for harm to six life-areas from one's own drinking and for assault by another drinker rose steadily with the respondent's volume of alcohol consumption. While drinking five or more drinks on an occasion at least once a month substantially raised the risk at a given volume of drinking, the risk rose with volume even among those not regularly drinking five or more drinks. These relationships remained in logistic regressions which controlled for gender, age and educational level. Younger respondents, those without higher education and men reported more harm for a given level of their own drinking although differences by gender disappeared above one-third of one drink per day. Three sets of guidelines for low-risk drinking--two from Canada, and one generally used in Britain--were compared in terms of the proportions of respondents reporting harm from their own drinking among those who had kept within the guideline in the previous 7 days' drinking. More restrictiveness in the guidelines was associated with substantial reductions in reported drinking-related harm.