Marijuana has been shown to be one of the commonly abused substances in the world, especially among teenagers and young adults. Although its addictive potential and psychomotor side-effects have been widely publicized, the issue of possible carcinogenicity is not as well perceived. Marijuana smoke contains many of the same organic and inorganic compounds that are carcinogens, co-carcinogens, or tumor promoters found in tobacco smoke. We have encountered several young marijuana users with no history of tobacco smoking or other significant risk factors who were diagnosed to have lung or other aero-digestive cancers in our practice. Although there are several experimental and epidemiological studies suggesting an association of marijuana use as a possible cause of cancers, this issue remains controversial. It is hoped that our case presentation can help to stimulate further awareness and research into this issue.