The present study investigated the utility of the International Classification of Diseases and Related Health Problems, 10th edition (ICD-10) diagnostic criteria for postconcussion syndrome (PCS) symptoms by comparing symptom endorsement rates in a group of patients with mild traumatic brain injury (MTBI) to those of a noninjured control group at one month and three months post-injury. The 110 MTBI patients and 118 control participants were group-matched on age, gender, and education level. Seven of the nine self-reported ICD-10 PCS symptoms differentiated the groups at one month post-injury and two symptoms differentiated the groups at three months post-injury: symptom endorsement rates were higher in the MTBI group at both time periods. Fatiguing quickly and dizziness/vertigo best differentiated the groups at both time periods, while depression and anxiety/tension failed to differentiate the groups at either time period. Collectively, the ICD-10 PCS symptoms accurately classified the MTBI patients at one month post-injury, with the optimal positive test threshold of endorsement of five symptoms coinciding with a sensitivity and specificity of 73% and 61%, respectively. The ICD-10 PCS symptoms were unable to accurately classify the MTBI patients at three months post-injury.