We assessed the association between gender identity disorder (GID) diagnosis and suicide in a retrospective case-control study (N=300,364) from nine health care systems between 2000 and 2015. Adjusting for age and sex, the odds ratio for GID was 18.6 (95% confidence interval 7.0-49.5). Adjusting additionally for comorbid psychiatric diagnoses, the odds ratio was 4.75 (1.78-12.68), higher than depressive (3.96, 3.64-4.31), alcohol use (3.42, 3.04-3.84), bipolar (2.42, 2.10-2.80), and psychotic disorders (1.44, 1.22-1.70). These U.S. data support prior research demonstrating increased suicide risk among patients with diagnosed GID, who may benefit from targeted screening and intervention within health care systems.