Sexualized drug use or "chemsex" in Taiwan commonly incorporates the use of methamphetamine. Our study aimed to assess the extent of severity of dependence of methamphetamine among MSM in Taiwan as well as motivations for engagement in chemsex. Direct messages were sent to users of a large MSM social networking application in Taiwan between November 2018 and January 2019. MSM who had at least one experience of using drugs during sex in the preceding 12 months were invited to complete an online survey that assessed their sexual behavior, substance use and motivations for engaging in chemsex. The Severity of Dependence Scale was used to assess methamphetamine dependency. Multivariable logistic regression was used to determine the factors associated with methamphetamine dependency. From a total of 1906 responses, 517 had used methamphetamine in their lifetime and were included in the analysis. The majority (87.2%) used more than one substance when engaging in chemsex in the past six months, while a quarter reported injection of methamphetamine within the last six months. The most commonly reported motivations for participants to engage in chemsex were to have fun, for relaxation, and to increase the intensity of the sexual experience. Nearly half (46.0%) exhibited signs of methamphetamine dependency. Lower monthly income, injection of methamphetamine, ever feeling lonely in the past 3 months and concerns about their substance use expressed by others were significantly associated with methamphetamine dependency. A high proportion of MSM population who engaged in chemsex were at risk of developing methamphetamine dependency. While motivations for engaging in chemsex were diverse and suggest potential for enhanced sexual experience for some, community health organization for gay men's health and healthcare providers should be vigilant at identifying the risk of methamphetamine dependency and provide in-time, brief intervention or referrals when needed. Copyright © 2021. Published by Elsevier B.V.