Background: Patient safety is in jeopardy due to a rise in the preparation of adulterated parenteral products with poor technique identified as a significant contributing factor. Pharmacy technicians perform an overwhelming majority of aseptic compounding practices; however, this group’s progressive loss of aseptic technique knowledge has not been documented. Objective: The purpose of this correlational research study was to investigate the association between sterile compounding knowledge and years in the field controlling for formal training in sterile compounding techniques. Methods: An assessment tool of fundamental sterile compounding content was electronically distributed to sterile compounding technician members of pharmacy organizations in the southeastern United States. A multiple regression was conducted to predict sterile compounding knowledge from number of years in the field and prior years of formal compounding training. Results: Sixty-eight assessments were returned complete. The overall model was significant ( P < .0005), explaining 22% of the variance in knowledge retention. Years in the field was the only significant predictor ( P < .001). Each additional year of work experience was associated with a 0.18 drop in the assessment score. Conclusions: The longer pharmacy technicians remain in the field, the more aseptic technique knowledge they will lose. Modeling of poor sterile compounding techniques in the workplace may promote loss of competency of the skill. As a result, a plan to address continuing education for pharmacy technician sterile compounders is necessary to ensure patient safety.