Drug use during sex ('chemsex') has been associated with sexually transmitted infections (STIs) and mental health harms. Little quantitative evidence exists on the health care needs of MSM practicing chemsex from a patient perspective. This study assessed self-perceived benefits and harms and the needs for professional counselling among MSM practicing chemsex. In 2018, 785 MSM were recruited at nine Dutch STI clinics and 511 (65%) completed the online questionnaire. Chemsex was defined as using cocaine, crystal meth, designer drugs, GHB/GBL, ketamine, speed and/or XTC/MDMA during sex <6 months. Chemsex was reported by 41% (209/511), of whom 23% (48/209) reported a need for professional counselling. The most reported topic to discuss was increasing self-control (52%, 25/48). Most MSM preferred to be counselled by sexual health experts (56%, 27/48). The need for professional counselling was higher among MSM who engaged in chemsex ≥2 times per month (30% vs. 17%, p = 0.03), did not have sex without drugs (sober sex) in the past three months (41% vs. 20%, p = 0.04), experienced disadvantages of chemsex (28% vs. 15%, p = 0.03), had a negative change in their lives due to chemsex (53% vs. 21%, p = 0.002), and/or had an intention to change chemsex behaviours (45% vs. 18%, p < 0.001). Our study shows that almost one in four MSM practicing chemsex expressed a need for professional counselling on chemsex-related issues. STI healthcare providers should assess the need for professional counselling in MSM practicing chemsex, especially in MSM with above mentioned characteristics, such as frequent users.