Switzerland has implemented a mandatory training in laboratory animal science since 1999; however a comprehensive assessment of its effects has never been undertaken so far. The results from the analysis of participants in the Swiss Federation of European Laboratory Animal Science Associations (FELASA) Category B compulsory courses in laboratory animal science run in 2010, 2012, 2014 and 2016 showed that the participants fully appreciated all elements of the course. The use of live animals during the course was supported and explained by six arguments characterized with cognitive, emotional and forward-looking factors. A large majority considered that the 3R (replacement, reduction and refinement) principles were adequately applied during the course. Responses to an open question offered some ideas for improvements. This overall positive picture, however, revealed divergent answers from different subpopulations in our sample (for example, scientists with more hindsight, scientists trained in biology, or participants from Asian countries).