['Alcohol-related motor vehicle collisions (MVCs) are a key concern in current international debates about the effectiveness of minimum legal drinking age (MLDA) laws, but the majority of this literature is based on natural experiments involving MLDA changes occurring 2-4 decades ago.', 'A regression-discontinuity approach was used to estimate the relation between Canadian drinking-age laws and population-based alcohol-related MVCs (n=50,233) among drivers aged 15-23years in Canada.', 'In comparison to male drivers slightly younger than the MLDA, those just older had immediate and abrupt increases in alcohol-related MVCs of 40.6% (95% CI 25.1%-56.6%; P<0.001) in Ontario; 90.2% (95% CI 7.3%-171.2%; P=0.033) in Manitoba; 21.6% (95% CI 8.5%-35.0%; P=0.001) in British Columbia; and 27.3% (95% CI 10.9%-44.5%; P=0.001) in Alberta; but also an unexpected significant decrease in the Northwest Territories of -102.2% (95% CI -120.7%-74.9%; P<0.001). For females, release from MLDA restrictions was associated with increases in alcohol-related MVCs in Ontario [34.2% (95% CI 0.9%-68.0%; P=0.044)] and Alberta [82.2% (95% CI 41.1%-125.1%; P<0.001)]. Nationally, in comparison to male drivers slightly younger than the legislated MLDA, male drivers just older had significant increases immediately following the MLDA in alcohol-related severe MVCs [27.0% (95% CI 12.6%-41.7%, P<0.001)] and alcohol-related fatal MVCs [53.4% (95% CI 2.4%-102.9%, P=0.04)].'] Is release from drinking-age restrictions associated with increases in alcohol-related motor vehicle collisions among young drivers in Canada?