Background and Purpose: There is an increasing number of evidence-based indications for pharmacogenetic (PGx) tests and a growing demand for PGx screening. We aimed to evaluate clinical relevance of a 16-gene panel test for PGx-guided pharmacotherapy. Experimental Approach: Observational cohort study of subjects tested with a PGx panel for variants of ABCB1, COMT, CYP1A2, CYP2B6, CYP3A4, CYP3A5, CYP2C9, CYP2C19, CYP2D6, CYP4F2, DPYD, OPRM1, POR, SLCO1B1, TPMT and VKORC1. Specialized clinical pharmacology consultations with PGx-guided pharmacotherapy management were supported by the PGx expert system SONOGEN XP. Study outcomes were PGx-based changes and recommendations regarding current and potential future medication. Key Results: PGx-testing was triggered by specific drug-gene pairs in 102 subjects, whereas screening was performed in 33. Based on PHARMGKB expert guidelines the 16-gene panel identified at least one “actionable” variant relevant for current or potential future medication in all 135 (100%) tested patients. Drugs that triggered PGx-testing were clopidogrel in 60, tamoxifen in 15, polypsychopharmacotherapy in 9, opioids in 7, and other in 11 patients. Among those, PGx variants resulted in clinical recommendations to change PGx-triggering drugs in 33 (32.4 %), and other current pharmacotherapy in 23 (22.5%). Conclusion and Implications: The 16-gene PGx panel detected clinically relevant variants in a high proportion of tested patients, and SONOGEN XP supported their interpretation based on latest evidence. Additional costs of panel vs. single gene tests are moderate, and the efficiency of PGx panel testing challenges traditional cost-benefit calculations for single drug-gene pairs. However, PGx-guided pharmacotherapy requires specialized consultations with interdisciplinary collaborations.