Although Avoidant Personality Disorder (AVPD) is associated with severe psychosocial impairment and is common in mental healthcare, it is an understudied condition. This study explored whether AVPD patients differ from patients with other Personality Disorders (PDs) in terms of general psychiatric symptoms and personality functioning. Hundred and twenty-four patients completed a test battery at admission to specialized treatment. Compared to patients with other PDs (n = 82), AVPD patients (n = 42) reported significantly higher levels of psychopathology. AVPD patients showed higher rates of maladaptive personality functioning. AVPD patients reported higher levels of general psychopathology and more signs of maladaptive personality functioning than patients with other PDs, indicating the seriousness of AVPD. These findings suggest a profile of instability, social isolation, and emotional inhibition with very weak identity integration and relational capacities for AVPD patients, although future research is needed to gain more insight in the clinical profile of AVPD.