Insomnia and nightmares are present in up to 45 % of individuals with borderline personality disorder (BPD) and can contribute to challenges with emotion regulation, low sleep quality, dream anxiety, increased arousal and self-control. Despite their prevalence, nightmares are usually not addressed in classical BPD treatment. Imagery rehearsal therapy (IRT) is considered first in line treatment for nightmares, however, there are no studies to date that investigate its effects in individuals with BPD. Here we investigated a) whether IRT can be used to treat nightmares in individuals with BPD and b) whether there is an additional benefit of the intervention on symptoms associated with BPD. In a between-subjects design, 22 individuals with BPD completed eight sessions of group-IRT as an add-on to their inpatient treatment and were compared to 22 gender and age matched control participants regarding nightmares, trauma, depression and anxiety symptoms. Nightmare symptoms improved significantly during the intervention as indicated by subjective ratings. Moreover, participants in the IRT group showed a more pronounced decrease in intrusions, hyperarousal and anxiety compared to the control group. This pilot study gives a first glimpse into the feasibility and benefits of imagery rehearsal therapy in individuals with BPD. Our findings suggest that IRT may not only help treat nightmare symptoms but also reduce anxiety and trauma symptoms in BPD. Future studies should include randomized controlled trials of IRT in individuals with BPD with larger sample sizes and polysomnography in both groups.