Autism spectrum disorder (ASD) is a heterogeneous neurodevelopmental disorder characterized by pervasive deficits in communication and social interaction and patterns of repetitive, restrictive interests and/or stereotyped behaviors. Female sex/gender is not represented in the current conceptualization of ASD, and there is emerging evidence of a female phenotype. The etiology of ASD and borderline personality disorder (BPD) is not fully understood. Clinical observations suggest that ASD and BPD can overlap in clinical presentation and diagnostic characteristics, especially in female ASD cases.We report two clinical cases of two adolescent girls presenting overlap symptoms between ASD and BPD, raising questions about the female ASD phenotype and the potential misdiagnosis of ASD characteristics with BPD, as well as its impact on diagnosis and management.Diagnostic differentiation is crucial for targeted therapeutic interventions (psychopharmacological and psychosocial). Further studies are needed to enlighten the clinical similarities and diagnostic overlap between ASD females and BPD.