Background and aims: Loot boxes are a common feature in video games where players win, buy or are gifted a virtual box or other container that is unwrapped to reveal virtual items of value, such as skins, weapons, in-game currency or special abilities. The current study aimed to relate the use of loot boxes to gambling problems and harm. Methods: An online survey was conducted with 1,954 adolescents and young adults from NSW Australia, 59.9% female (aged 12-24), recruited by online panel aggregator, Qualtrics. Results: Buying and selling loot boxes was associated with higher 12-month gambling frequency and gambling problems in young adults, aged 18-24 (Problem Gambling Severity Index). Young adults who bought loot boxes additionally had more gambling-related harms (Short Gambling Harms Screen). Young women, aged 18-24, who opened, bought and/or sold loot boxes spent more money in the last 12 months on gambling. In adolescents, aged 12-17, buying loot boxes was similarly associated with gambling problems (DSM-IV-MR-J). Furthermore, adolescent girls who bought and/or sold loot boxes viewed gambling more positively than other girls (Attitudes Towards Gambling Scale). There was no evidence, however, that longer-term experience in opening or purchasing loot boxes, a differentiating feature of the survey, is associated with current gambling problems. Discussion and conclusions: This study suggests that loot boxes may be attractive to people who are already predisposed to engage in other gambling, and females who use loot boxes may have unique vulnerabilities to gambling problems that could be explored in future research.  Kulcsszavak: gaming, games, video games, online gaming, loot boxes