Purpose To evaluate the prevalence of, and risk factors for, early endocrine disorders in childhood brain tumor survivors (CBTS). Patients and Methods This nationwide study cohort consisted of 718 CBTS who were diagnosed between 2002 and 2012, and who survived ≥ 2 years after diagnosis. Patients with craniopharyngeoma or a pituitary gland tumor were excluded. Results of all endocrine investigations, which were performed at diagnosis and during follow-up, were collected from patient charts. Multivariable logistic regression was used to study associations between demographic and tumor- and treatment-related variables and the prevalence of early endocrine disorders. Results After a median follow-up of 6.6 years, 178 CBTS (24.8%) were diagnosed with an endocrine disorder. A total of 159 CBTS (22.1%) presented with at least one endocrine disorder within the first 5 years after diagnosis. The most common endocrine disorders were growth hormone deficiency (12.5%), precocious puberty (12.2%), thyroid-stimulating hormone deficiency (9.2%), and thyroidal hypothyroidism (5.8%). The risk of hypothalamic-pituitary dysfunction (n = 138) was associated with radiotherapy (odds ratio [OR], 15.74; 95% CI, 8.72 to 28.42), younger age at diagnosis (OR, 1.09; 95% CI, 1.04 to 1.14), advanced follow-up time (OR, 1.10; 95% CI, 1.02 to 1.18), hydrocephalus at diagnosis (OR, 1.77; 95% CI, 1.09 to 2.88), and suprasellar (OR, 34.18; 95% CI, 14.74 to 79.29) and infratentorial (OR, 2.65; 95% CI, 1.48 to 4.74) tumor site. Conclusion The prevalence of early endocrine disorders among CBTS is high. The observation that 22.1% of CBTS developed at least one endocrine disorder within the first 5 years after diagnosis stresses the importance of early and regular assessment of endocrine function in CBTS who are at risk for endocrine damage.