Abstract Background The opening up of legislation on medicinal cannabis in recent years has been a determining factor in the growth of this therapy. In Europe, regulation of medicinal use is a reality in several countries. Nurses can play a leading role in its administration, helping to ensure that it is carried out more effectively and assuming a fundamental role in the success of the therapy. It is therefore pertinent to analyze the knowledge of nurses and nursing students in Portugal about medicinal cannabis. Methods Quantitative descriptive study. A self-completion questionnaire was drawn up and made available on the google forms platform. It was face-validated, content-validated and approved by the Ethics Committee. The instrument included sociodemographic data, questions about cannabis knowledge and perspectives. Descriptive statistics were analyzed. Results Out of a total of 610 responses, 318 were nurses and 292 nursing students. Medical cannabis is considered legitimate by 79.6% of nurses and 84.3% of students. When asked about the functions of the endocannabinoid system, 71.7% of nurses and 79.5% of students said they had no knowledge. 88.7% of nurses and 79.5% of students disagreed that they had sufficient knowledge to advise users on the use of medicinal cannabis. Also, 38.4% believe that their patients use cannabis illegally to manage the symptoms of illnesses. Conclusions There is a need for continuing training for nurses and for the undergraduate and postgraduate nursing curricula to include this emerging area. Key messages • The results show that this issue is a public health problem. It reinforces the need to formulate public policies in this area and to implement training for nurses and nursing students. • These measures will be fundamental in preventing the use of illegal cannabis and promoting the safe use of medicinal cannabis.