Clinical observations suggest that individuals with panic disorder (PD) vary in their beliefs about the causes of their panic attacks. Some attribute these attacks to psychological factors, while others to physiological or medical factors. These beliefs also extend to whether individuals perceive panic attacks as dangerous. In other areas of psychiatric nosology, these phenomena are commonly called clinical insight (recognition of disorder and the need for treatment) and cognitive insight (the ability to reflect on one's beliefs). Despite its importance, limited research exists on insight in PD and its relation to symptoms and treatment outcomes. This study examines clinical and cognitive insight in 83 patients with PD who received internet-based cognitive behavioral therapy, investigating their relationship with symptoms, treatment outcomes, and changes in insight. We assessed patients using interview and self-report measures of insight and symptoms. Clinical and cognitive insight were correlated and both constructs improved significantly during treatment. Good clinical insight pretreatment was positively correlated with more severe pretreatment symptoms. Pretreatment clinical and cognitive insight were not correlated with symptom change or attrition. Greater change in clinical and cognitive insight was related to greater change in symptoms. The findings highlight the significance of clinical and cognitive insight in PD, and the importance of distinguishing between them. This suggests the need to develop interventions according to patients' level of insight, particularly focusing on those lacking insight. Further research is essential to advance our understanding of the relationship between insight and the phenomenology and treatment of PD.