Based on the cases in which assisted suicide (AS) has taken place in Switzerland in the context of a mental disorder or dementia, we discuss whether the slippery slope argument often brought up by opponents of assisted dying is justified. Long-term data from the Swiss Federal Statistical Office shows that while the number of cases with these «indications» is increasing (1999-2017: on average 21 cases/year vs. 2018-2022: n = 73 cases/year), the percentage share of these diseases in the total number of all AS cases has remained unchanged at around 5 %. Opponents of assisted dying believe that the slippery slope argument is already fulfilled by the fact that these cases occur at all. However, the still limited prevalence of these specific indications which still represent only a minority of assisted suicide cases over time, may be used by advocates of assisted dying to weaken the opposing viewpoint.