Background: Immune checkpoint inhibitors (ICI) are improving the care of cancer patients. Despite being better tolerated than chemotherapy, there is a risk of developing irAEs which may require hospitalization. Although ICI and irAEs are well studied in clinical trials, there is a paucity of studies characterizing the care patterns for real-world irAEs hospitalizations. Methods: A single centre retrospective chart review (Princess Margaret Cancer Centre, Toronto, ON) identified patients receiving standard of care ICI (2012-2017) hospitalized for irAEs. For hospitalizations, clinico-pathological, investigation and treatment details were collected. Descriptive statistics helped to characterize hospitalizations. Results: Among 697 patients (266 lung, 381 melanoma and 50 genitourinary (GU)) on ICI, 8% (14 lung, 41 melanoma and 2 GU) had at least 1 irAE (range 1-4) hospitalization for a total of 69 hospitalizations. Average length of stay was 12 days (range 1-105). Among hospitalized patients, median age was 60; 63% were male; 29% received ipilimumab monotherapy, 28% pembrolizumab, 22% nivolumab and 22% received combination ICI. The most common irAEs were colitis (52%), pneumonitis (20%), hepatitis (10%) and CNS disease (demyelination, hypophysis) (9%). Cases were admitted directly from clinic (39%), emergency rooms (29%), urgent care clinic (18%) or transferred from another hospital (13%). Most patients (72%) were admitted to oncology; 28% to general medicine. Endoscopy was performed in 21% of admissions with 60% showing evidence of irAE; biopsies were obtained in 16% of admissions and 73% had evidence of irAE. Subspecialty services were involved in 60% of admissions. Most patients received steroids (94%); 17% received Infliximab. While age did not impact length of stay (p = 0.63), patients admitted to oncology had longer admissions compared to general medicine (14 vs 6 days, p = 0.009). Conclusions: irAEs occur at similar rates in the real-world compared to clinical trials. There is significant heterogeneity in the care patterns for irAEs. Patients admitted to oncology had longer average lengths of stay. Further characterizing irAE can help to develop quality indicators that may improve irAE outcomes.