Outcomes of tonsillectomy (with or without adenoidectomy [w/woA]) in hospitalized children are unclear. We sought, to describe the characteristics of hospitalized children who underwent tonsillectomy (w/woA), to estimate the prevalence of complications and to evaluate the relative impact of different comorbid conditions (CMC) on the risk of occurrence of common complications following these procedures. All patients aged ≤21years who underwent a tonsillectomy (w/woA) were selected from the Nationwide Inpatient Sample (NIS 2001-2010). The associations between several patient/hospital-level factors and occurrence of complications were generated using multivariable logistic regression models. Over a decade, a total of 141 599 hospitalized patients underwent tonsillectomy (w116 319; woA 25 280). A total of 58.1% were males. Majority of the procedures were performed in teaching hospitals (TH, 73.7%), in large (bed-size) hospitals (LH, 57.8%), and in those who were electively admitted (EA, 67.3%). Frequently present CMC in patients included obstructive sleep apnea (OSA, 26.4%), chronic pulmonary disease (CPD, 14.6%), neurological disorders (ND, 6.7%), and obesity (4.8%). Majority of patients were discharged routinely (98%). Overall complication rate was 6.4% with common complications being postoperative pneumonia (2.3%), bacterial infections (1.4%), respiratory complications (1.3%), and hemorrhage (1.2%). All-cause mortality included a total of 60 patients. Patients in TH (odds ratio [OR] = 0.72, 95%CI = 0.62-0.85), LH (OR = 0.80, 95% CI = 0.69-0.93), and those who had the procedures during EA (OR = 0.64, 95% CI = 0.56-0.74) had significantly lower odds of complications compared with their counterparts. CMC such as anemia, CPD, coagulopathy, HT, ND, and fluid/electrolyte disorders were independent predictors of significantly higher complication risk (P < .05). In conclusion, hospitalized children who underwent tonsillectomy (w/woA) in large or teaching hospitals, or during elective admissions had lower risk of complications. Comorbidity is an important independent predictor of complications in this cohort.