Objective: To assess effects of centrifugation time and relative centrifugation force in pre-analytical procedure on results of glucose, urea, creatinine, triglyceride, cholesterol, HDL-cholesterol, LDL - cholesterol, aspartate aminotransferase (AST), alanine aminotransferase (ALT), gamma glutamyl transferase (GGT), acid uric, total bilirubin, direct bilirubin in plasma samples.