This study addresses the issue of the underreporting of suicide in Canadian vital statistics, and specifically asks whether the degree of underreporting can be assumed to be even across levels of commonly studied sociodemographic variables, across time, and among the ten provinces.;The analysis involves a series of comparisons between cause-specific accident and suicide rates and the same rates with deaths of undetermined origin added, over time. Data pertaining to these latter deaths have been collected in Canada since 1969; research in other jurisdictions has demonstrated that most of these deaths could be considered misclassified suicides for research purposes in psychiatric epidemiology.;The results tend to confirm the findings of other researchers, specifically that suicide is probably underreported more among females and in cases of drowning and poisoning; the findings suggest as well that some provinces account for a disproportionate share of deaths of undetermined origin which may be sufficient to introduce regional differences in underreporting. The potential underreporting of suicide was found to peak in the mid to late 1970s in Canada, and was found not to vary significantly across age groups within the same sex and cause.;With the exception of age, the assumption of a constant error in the underreporting of suicide seems to be unjustified. This lack of constancy is argued to pose a negligible threat to most descriptive epidemiologic uses of official suicide statistics. Examples are given in which suicide statistics, corrected for potential underreporting, yield the same general conclusions regarding relative prevalence between groups as do the uncorrected statistics.;By contrast, the uneven underreporting is argued to represent a potential threat to some inferences derived from explanatory studies that use suicide statistics, because of the widespread testing of hypotheses using probability statistics. One simple method to strengthen some statistical inferences is presented, and its limitations are discussed
