Patient access to electronic health records (EHRs) is associated with improved efficiency, self-management, and patient engagement. However, the EHR contains medical language that can be difficult to comprehend by patients. In Dutch hospitals, the Diagnosethesaurus (DT) is used as an interface terminology to register diagnoses, but it does not contain patient-friendly terms. Fortunately, the DT is partly mapped to SNOMED CT and there is a proportionately small set of patient-friendly terms available in the Dutch SNOMED CT release. The purpose of this study was, therefore, to investigate if SNOMED CT can be used to generate clarifications of diagnoses for patients. Only 1.2% of the DT diagnoses that were already mapped to SNOMED CT had patient-friendly synonyms that were different from the diagnoses descriptions. However, by generalizing diagnoses to SNOMED CT concepts with patient-friendly terms, this number could be increased to 71%. In conclusion, we showed that a high percentage of diagnoses could be clarified to at least some extent with the relatively small set of patient-friendly terms. Future research will involve the further optimization of the clarifications, and evaluation with clinicians and patients.