Background: Age is among the most important risk factors for neutropenia-related hospitalization, but evidence is limited regarding the relative contributions of age and other risk factors. Objective: To explore the associations among patient age, other risk factors, and neutropenic complications in patients with cancer receiving myelosuppressive chemotherapy. Methods: This retrospective cohort study, which used a US commercial insurance claims database, included patients aged 40 years or older with non-Hodgkin lymphoma (NHL), breast cancer, or lung cancer who initiated chemotherapy between January 1, 2006 and March 31, 2010. The primary endpoint was the risk of neutropenia-related hospitalization during the first chemotherapy course. We used cubic spline modeling to estimate the association between neutropenia-related hospitalization and age, adjusting for patient and treatment characteristics. Logistic regression analyses examined the effects of other risk factors. Results: A total of 15,638 patients were included (NHL, n = 2,506; breast cancer, n = 9,110; lung cancer, n = 4,022), mean age 56-66 years. Neutropenia-related hospitalization occurred in 8.7% of NHL patients, 4.2% of breast cancer patients, and 3.9% of lung cancer patients. The association between age and the risk of neutropenia-related hospitalization was stronger in NHL than in lung or breast cancer. Patient comorbidities and chemotherapy characteristics had considerable effects on risk of neutropenia-related hospitalization. Limitations: Disease stage and other clinical factors could not be identified from the claims data. Conclusion: In addition to age, oncologists should evaluate individual patient risk factors including patient comorbidities and type of chemotherapy regimen.