OBJECTIVES: This study aimed to elucidate the hospitalization costs of adverse events (AEs) commonly associated with treatments for metastatic melanoma. METHODS: Based on current drug labels and published clinical studies for the treatments of metastatic melanoma, 23 serious adverse events were identified. Length of stay (days) and hospitalization costs (2013 US $) for these 23 events (identified by primary discharge diagnoses) were examined using a large national claims database, in which patients with metastatic melanoma were identified from July 2004 to November 2012. All analyses are presented descriptively. RESULTS: There were 2998 patients with metastatic melanoma: most were male (59.5%) and the mean age was 55.8 years old.  Hospitalizations due to acute myocardial infarction and sepsis incurred the longest median length of stay (9 and 6 days, respectively), followed by acidosis (5.5 days), acute kidney failure, pneumonitis, neuropathy, thrombocytopenia, and oliguria/anuria (all had 5 days). The highest inpatient cost per event was for acute myocardial infarction (mean $45,971 and median $53,747), followed by sepsis ($34,351 and $22,838), coma ($30,943 and $23,149), acute kidney failure ($30,485 and $19,972), neuropathy ($28,977 and $12,034), and pneumonitis ($27,669 and $21,011). Colitis/diarrhea, cutaneous squamous cell carcinoma, thrombocytopenia, hyponatremia, oliguria/anuria, hypertension, anemia, and elevated liver enzymes were associated with mean costs per hospitalization ranging from $26,234 to $18,676. In contrast, the lower inpatient cost per event was for cellulitis (mean $16,828 and median $12,045), fever ($15,078 and $13,650), rash ($14,432 and $12,086), and nausea ($13,715 and $10,892).  CONCLUSIONS: Hospital costs for the management of adverse events vary greatly. This study provides source data for economic evaluation of treatments for metastatic melanoma.