Background: Research indicates that psycho-education and cognitive behavioural interventions can reduce perfectionism but to date no group treatments have been examined. Aims: The current study utilized a case series design to compare psycho-education materials and subsequent eight-week group cognitive behaviour therapy (CBT) to a baseline waitlist in an outpatient community psychiatry sample (n = 21). Method: Participants were assessed on five occasions: baseline, 4 weeks later (waitlist), 4 weeks after receiving psycho-education material, post-treatment (8 weeks after receiving the group intervention), and 3-month follow-up. Results: There was a main effect of time for perfectionism and negative affect from baseline to post-group (effect sizes ranging from 1.46 to 1.91) that were maintained at 3-month follow-up. Conclusions: These results suggested that group CBT for clinical perfectionism may be beneficial, but that psycho-education alone is not effective for reducing perfectionism or negative affect.