Carers of persons with borderline personality disorder (BPD) experience high burden. Treatment guidelines advocate involving carers in comprehensive therapy approaches. This study is a randomized controlled trial of group psychoeducation, compared to waitlist. Group psychoeducation involved 6–8 carers per group and focused on improving relationship patterns between carers and relatives with BPD, psychoeducation about the disorder, peer support and self-care, and skills to reduce burden. Carers were randomized into intervention (N = 33) or waitlist (N = 35).