Purpose <p>Although already a lot of research has been done on pharmacogenetic tests to inform the choice and/or dosing of medicines, the implementation and clinical uptake remain limited. This study assessed the implementation of pharmacogenetic (PGx) testing on a national scale by analyzing access to and volumes of reimbursed PGx.</p> Methods <p>The use of pharmacogenetic tests was examined via a cross-sectional online survey among the Belgian laboratories, collecting data on PGx targets, testing volumes and technologies used. The focus was on reimbursed tests. Additional data were sourced from the national reimbursement database to describe uptake of testing per medication.</p> Results <p>The uptake of PGx testing in Belgium varied by medication, with significant implementation for fluoropyrimidines, abacavir, and thiopurines. DPYD gene testing was the most frequently performed PGx test, due to endorsed (inter)national guidelines. Reimbursement rules shape access to PGx, with the majority of PGx tests performed in dedicated centers for human genetics (CHG). Access to HLA laboratories for HLA targets was not optimal and some laboratories without a CHG also included constitutional PGx targets in somatic oncology panels.</p> Conclusion <p>This nationwide study demonstrates that in a country where the prescribers have access to a relatively extensive list of reimbursable PGx tests, the implementation of PGx testing is shaped by the presence of endorsed evidence-based clinical practice guidelines, as well as organizational and logistical factors.</p>