Completed suicide (CS) is a leading cause of death worldwide and its rates are available for most developed countries. On the other hand, attempted suicide (AS) is a risk factor for CS but there are limited data on its rates in various countries. In constructing a ratio for AS/CS rates, most would agree that for CS, the denominator should be the annual suicide rate (per 100 000). As for the ratio's numerator (AS) per 100 000, there are three possible calculations: (1) annual prevalence from population surveys, (2) annual prevalence from national clinical registers or (3) lifetime prevalence from population surveys. We think that the first possibility would probably be the best choice but, unfortunately, surveys providing the annual prevalence of AS are lacking for most countries. Annual prevalence from national registers is also lacking for most countries and is contaminated by under-reporting. Therefore, in this editorial, we are left with only the last option, a ratio for lifetime prevalence of AS (per 100 000) divided by annual rate of CS (per 100 000). This ratio for AS/CS rates appears to differ substantially across countries worldwide but presents no big regional differences other than two remarkable exceptions, one per continent. In Europe, Spain and France had greater ratios (174.4 and 152.5, respectively) than Italy (64.1). In Asia/Pacific, New Zealand has a higher ratio (345.9) compared with China (75.8) and Japan (76.9). The ratio for AS/CS rates could be a good index for implementing evidence-informed decision-making regarding suicidal behaviour (SB) among health service managers, and for helping them in the allocation of health resources for the prevention of SB.