OBJECTIVES: Procalcitonin (PCT) is a relatively novel biomarker that may be superior to C-reactive protein (CRP) in identifying bacterial infection. PCT use in pediatric hospitals is relatively unknown. We aimed to evaluate PCT and CRP use, describe PCT testing variability across children’s hospitals, and compare temporal rates of PCT and CRP testing for patients admitted with pneumonia, sepsis, or fever in young infants. METHODS: In this multicenter cohort study, we identified children ≤18 years old hospitalized from 2014–2018 with pneumonia, sepsis, or fever in infants <2 months by using the Pediatric Health Information System. To determine use, we evaluated the proportion of encounters with PCT or CRP testing from 2017-2018. We generated heat maps to describe PCT use across hospitals. We also compared PCT and CRP rates over time from 2014 to 2018. RESULTS: From 2017–2018, PCT testing occurred in 3988 of 34c231 (12%) hospitalizations. Febrile infants had the highest PCT testing proportion (18%), followed by sepsis (15%) and pneumonia (9%). There was across-hospital variability in PCT testing, particularly for febrile infants. Over time, the odds of PCT testing increased at a significantly greater rate than that of CRP. CONCLUSIONS: Despite limited guideline recommendations for PCT testing during the study period, PCT use increased over time with across-hospital variability. For pneumonia and sepsis, given the importance of high-value care, we need to understand the impact of PCT on patient outcomes. With recent guidelines recommending PCT in the evaluation of febrile infants, we identified baseline testing behaviors for future studies on guideline impact.