To check the adherence to the immunosuppressive treatment of post-renal transplant patients. Method: This is a quantitative, transversal, descriptive-exploratory study performed using 50 patients in the Brazilian state of Santa Catarina. The study involved a semistructured interview based on the "Measurement Test of Adherence to Treatments". Results: It was observed that 76% of the patients were considered to be non-adherent to the immunosuppressive treatment; in 62% of the cases it was unintentional behavior; 2% of the cases mentioned lack of motivation to continue treatment; 44% of the cases ingested from 11 to 15 pills/day. The complications reported were hypertension, diabetes and graft rejection. Discussion: Besides the non-adherence, patients demonstrated understanding and motivation regarding the medication. The excessive umber of drugs ingested on a daily basis influenced the adherence to the treatment. There were two chronic rejections, one of which presented a connection to non-adherence to the immunosuppressive treatment. Conclusion: The number of medications contributed to non-adherence.