OBJECTIVES: Delayed chemotherapy-induced nausea and vomiting (CINV) can increase healthcare utilization and decrease patient quality of life. While reports of delayed CINV range from 40-60% with moderately to highly emetogenic regimens, little information is available on utilization of care as a result. To determine the frequency of outpatient service utilization associated with CINV between 24-120 hours following chemotherapy administration during cycles 1-5. METHODS: A retrospective observational design of US Oncology nation-wide iKnowMed electronic medical records (EMR) was employed. The cohort for analysis included patients from four practices in separate states receiving chemotherapy between August 2004 and April 2005. Chemotherapy regimens included one or more of the following five drugs: carboplatin, cisplatin, oxaliplatin, doxorubicin, cyclophosphamide. Failure was defined as one or more of the following events between 24-120 hours following chemotherapy: phone encounters with documentation of CINV; non-chemotherapy office visits for hydration, IV anti-emetic administration, and/or documentation of CINV; oral anti-emetic orders between 24-120 hours. RESULTS: A total of 691 patients were identified as receiving target chemotherapies during cycles 1-5. Mean (std) age was 61 (13) years, and 62% were female. Twenty-six percent had breast cancer, 26% lung, 10% colorectal, and 8% lymphoma. In cycle 1, the rate of failure was 6.7%; in cycle 2, 5.9%; in cycle 3, 5%; in cycle 4, 5.3%; and in cycle 5, 4.0%. All patients received one or more IV anti-emetic on Day 1 of each cycle. CONCLUSION: The rates reported in this cohort of patients from a nation-wide EMR database indicate that while many patients may experience some degree of CINV during days 2-5 of chemotherapy, only a small percentage receive outpatient clinic care as a result.