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Background and Importance Pharmacogenetics (PGx) enables the identification of genetic variants that influence drug metabolism, efficacy, and safety. Implementation of pharmacogenetic testing in clinical practice allows optimisation of pharmacotherapy, particularly in polymedicated patients. In Spain, initiatives such as the CSVS and CEGEN-CNIO projects have promoted the development of population-specific PGx databases. However, real-world data from hospital settings remain limited.Aim and Objectives To describe the demographic and pharmacogenetic profile of patients analysed in the Spanish Hospital as part of the national pharmacogenetic implementation project, in order to evaluate the frequency of actionable variants and identify potential clinical relevance.Material and Methods An observational descriptive study was conducted including patients with available pharmacogenetic testing performed at CEGEN-CNIO using Illumina Infinium technology. Demographic variables (age, sex, diagnosis, medication) and pharmacogenetic results (genotype and phenotype of key pharmacogenes) were analysed. Descriptive statistics were performed using R and RStudio V4.5.1.Results A total of 40 patients were included (70% male; mean age 40 years, range 25–75). The most frequent diagnoses were gastritis (22.5%), oesophagitis (7.5%), hypertension (7.5%), hypercholesterolaemia (5%) and major depression (5%). The mean number of concomitant drugs per patient was 2.1 (maximum 12). Across the pharmacogenetic panel, 196 phenotypes were classified as normal metabolisers, 56 as intermediate, 39 as poor, and 11 as rapid metabolisers. Approximately one-third of patients carried at least one actionable variant.Interestingly, the overall prevalence of altered phenotypes was slightly lower than that reported in broader European cohorts (where up to 90–99% of individuals carry at least one actionable variant), suggesting possible population-specific differences or the effect of sample selection. This reinforces the need for local pharmacogenetic studies integrated into hospital practice.Conclusion and Relevance Our findings highlight relevant interindividual variability in drug metabolism, although with a lower frequency of altered genotypes compared to European reference populations. This underlines the importance of implementing pharmacogenetic testing within hospital settings to ensure accurate, population-adapted precision medicine strategies. Proactive integration of PGx results into electronic health records could enhance therapeutic safety, efficacy, and cost-effectiveness within the Spanish National Health System.Conflict of Interest No conflict of interest