Background and purpose - Attachment theory provides an integrative perspective about the interplay between cognitive, affective, behavioral and interpersonal processes and is relevant for understanding irritable bowel syndrome (IBS) and panic disorder (PD). The aim of the present study was to examine the adult attachment style and parental bonding of IBS and PD patients. Methods - In a cross-sectional questionnaire-based study, 65 PD and 65 IBS patients with clinical diagnosis participated. Measures were Attachment Style Questionnaire, Experiences in Close Relationships Scale - Revised, and Parental Bonding Instrument. Results - The frequencies of insecure attachment (80.0% vs. 63.1%) and paternal neglect (35.4% vs. 16.9%) were higher in IBS than in PD (χ2 (1)=4.571, p=0.033, and χ2 (3)=7.831, p=0.050, respectively). The frequency of secure attachment was significantly higher for optimal paternal bonding than with suboptimal paternal bonding (75.0% vs. 21.9%, χ2 (1)=19.408, p<0.001). According to the results of multiple binary logistic analysis, optimal paternal bonding predicted secure attachment after adjusting for the background variables (OR=9.26, p=0.001). Conclusion - A high frequency of insecure attachment was present in both groups, especially in IBS. With regard to maternal bonding, IBS and PD groups showed similar patterns, while an apparent difference was observed for paternal bonding. These highlighted the developmental similarities of these two, symptomatically different disorders. While optimal maternal bonding did not predict adult attachment security, paternal bonding did thus replete with therapeutic implications. Attachment functions, like responsiveness, attunement and affection modulation were apparent in the psychotherapist-patient relationship as well.