In recent years, US hospitals have switched from use of unfractionated heparin to use of low-molecular-weight heparin, which is associated with lower risk of heparin-induced thrombocytopenia (HIT). In the study reported here, we retrospectively searched the Nationwide Inpatient Sample (NIS) for patients who were at least 18 years old and received a diagnosis of HIT between 2009 and 2011. Our goal was to get an updated perspective on the incidence and economic impact of HIT. We calculated the incidence of HIT overall and in subgroups of patients who underwent cardiac, vascular, or orthopedic surgery. We compared characteristics of patients with and without HIT and compared characteristics of patients with HIT with thrombosis (HITT) and HIT patients without thrombosis. Of 98,636,364 hospitalizations, 72,515 (0.07%) involved HIT. Arterial and venous thromboses were identified in 24,880 (34.3%) of HIT cases. Men were slightly more likely to have a HIT diagnosis (50.1%), but women had higher rates of HIT after cardiac surgery (odds ratio [OR], 1.41; 95% confidence interval [CI], 1.26-1.58) and vascular surgery (OR, 1.42; 95% CI, 1.29-1.57). Rates of HIT were 0.53% (95% CI, 0.51%-0.54%) after cardiac surgery, 0.28% (95% CI, 0.28%-0.29%) after vascular surgery, and 0.05% (95% CI, 0.05%-0.06%) after orthopedic surgery. HIT and HITT cases were significantly (P ⟨ 0.001) more likely than non-HIT cases to be fatal (9.63% and 12.28% vs 2.19%), and they had significantly higher costs and longer inpatient stays. HIT and especially HITT are associated with increased mortality, costs, and length of stay. Journal of Hospital Medicine 2017;12:94-97.