Febrile neutropenia (FN) is a potentially fatal complication of chemotherapy. This prospective, observational study describes physicians' approaches toward assessing FN risk in patients receiving chemotherapy regimens with an intermediate (10-20 %) FN risk. In the baseline investigator assessment, physicians selected factors considered important when assessing overall FN risk and deciding on granulocyte colony-stimulating factor (G-CSF) primary prophylaxis (PP). Physicians then completed patient assessments using the same lists of factors. The final FN risk scores and whether G-CSF PP was planned were reported. The final analysis included 165 physicians and 944 patients. The most frequently considered factor in both assessments was chemotherapy agents in the backbone (88 % of investigator and 93 % of patient assessments). History of FN (83 %), baseline laboratory values (76 %) and age (73 %) were commonly selected at baseline, whereas tumor type (72 %), guidelines (62 %) and tumor stage (43 %) were selected most during patient assessments. Median investigator-reported FN risk threshold for G-CSF PP was 20 % (range 10-85 %). G-CSF PP was planned in 82 % of patients with an FN risk at or above this threshold; therefore, almost one-fifth of qualifying patients would not receive G-CSF PP. Physicians generally follow guidelines, but also consider individual patient characteristics when assessing FN risk and deciding on G-CSF PP. A standardized FN risk assessment may optimize the use of G-CSF PP, which may minimize the incidence of FN in patients undergoing chemotherapy with an intermediate FN risk. ClinicalTrials.gov Identifier: NCT01813721.