Background: Many cancer chemotherapy patients who are candidates for CP do not receive it, while others receive it inconsistent with established guidelines (e.g., on same day as chemotherapy). The objective of this study was to characterize episodes, outcomes, and costs of FNH among cancer chemotherapy patients for whom CP is recommended, by use and patterns of CP. Methods: From US private healthcare claims repositories (2005-13), study subjects included adults who received a chemotherapy course with an NCCN-listed high-risk regimen or intermediate-risk regimen (if ≥ 1 FN risk factor present) for non-metastatic breast cancer or non-Hodgkin’s lymphoma (NHL); each cycle within the chemotherapy course and each FNH episode within the cycles were identified. Outcomes included mortality (all-cause) and inpatient days during the FNH; FNH-related costs were expressed in US$2013. Use (yes/no) of CP and patterns (by agent, administration day/duration) of CP were evaluated within cycles in which FNH occurred. Results: 58,320 subjects received AC/AC-T, TAC, or TC for non-metastatic breast cancer or CHOP±R for NHL. Among all FNH episodes (n = 6,355; rate = 109 per 1,000 patients), 41% occurred in patients who did not receive CP in that cycle, and 9% occurred in those who received CP on the same day as chemotherapy. Among FNH episodes occurring in patients who received daily CP (2% of total CP use), 56% received < 7 days of CP during the cycle. Findings for FNH outcomes and costs were comparable. Conclusions: In this retrospective evaluation, one-half of FNH episodes, outcomes, and costs among cancer chemotherapy patients who were candidates for CP occurred among those who either did not receive it or received it inconsistent with established guidelines.