Medication errors have long been considered critical in global health care systems. However, few studies have been conducted to explore the effects of nursing unit structure on medication errors. The purpose of this study, therefore, was to determine the effects of structural factors on medication errors in nursing units. A total of 977 staff nurses and 62 head nurses participated in this cross-sectional design study. The findings show that professional autonomy (β = .53, t = 6.03, p < .01), technology (β = .25, t = 3.02, p < .01), and nursing experts (β = .52, t = 5.99, p < .01) are predictors of medication error rates. This study shows that the structural factors influence medication administration and the mechanistic approach is specifically in relation of low medication error rates. The author suggests that head nurses should consider strategies that require adjustments to unit control mechanisms.