Objective Pharmacotherapy is established as an effective method for reducing symptoms of panic disorder (PD). However, about 20– 40% of PD patients are treatment-resistant. Predictors of pharmacotherapy outcomes for PD patients are needed. Methods This study included 152 PD patients to measure the clinical severities of PD symptoms and used the Early Trauma Inventory (ETI) to measure early trauma. Treatment response was defined as a 40% reduction in the total Panic Disorder Severity Scale score from baseline. We measured the treatment responses at 8 weeks and 6 months. Binary logistic regression was used to predict treatment response after controlling for confounding variables. Results Early sexual trauma alone was associated with poor treatment response at 8 weeks. However, at 6 months, the total ETI score was associated with an unfavorable treatment response. Conclusion Therefore, our study suggests that clinicians need to be aware of a history of early trauma to optimize treatment outcomes for PD patients.