Objective: Parents diagnosed with borderline personality disorder (BPD) are likely to find the emotional aspects of parenting challenging. Research into the difficulties that these parents experience, however, is lacking. The aims of the present study were to (i) gain an understanding of the interactional patterns of mothers with BPD and their infants and (ii) to explore the parenting perceptions of mothers with BPD., Method: Two groups of mother-infant dyads were recruited: mothers with BPD and their infants; and community mothers and their infants. Groups were compared on mother-infant interaction patterns and on maternal self-perceptions of parenting., Results: Mothers with BPD were found to be less sensitive and demonstrated less structuring in their interaction with their infants, and their infants were found to be less attentive, less interested and less eager to interact with their mother. Furthermore, mothers with BPD reported being less satisfied, less competent and more distressed., Conclusions: Early intervention needs to be provided to mothers with BPD to promote maternal sensitivity and maternal perceptions of competence.