Intravenous admixture preparation errors (IAPE) in hospitals are common and may result in harm if they reach the patient. In this before-and-after study, IAPE data were collected to evaluate the safety of a pharmacy-based centralized intravenous admixture service (CIVAS). Compared to the initial standard practice (nurse preparation on the ward), IAPE of all severity levels (i.e., potential error, no harm, harm) decreased and there were no errors in the highest severity level after implementation of CIVAS.