The CYP2D6 plays critical roles in drug metabolism, and its inter-individual variability should be properly addressed in clinical practice. Our research aimed to assess the performance of single-point saliva metabolic ratio (MR) in a healthy Chinese Han population using dextromethorphan as the probe drug. MR was determined as the ratio of parent drug to metabolite in 3 h saliva, 3 h plasma, and 0-3 h urine post-ingestion. 416 healthy volunteers were enrolled, with 290 (69.7%) male participants and a median body mass index (BMI) of 23.1 kg/m