Objectives: This study investigates whether the reverse interpretation of low Pa score in MMPI that indicate a paranoid tendency is appropriate. Methods: The 96 psychiatric patients perform MMPI and Rorschach test, and their clinical diagnosis and symptoms were evaluated. Study group is divided into high, middle and low Pa group on the basis of Pa score. Dependent variables were Rorschach Hypervigilance Index(HVI), content index related to the paranoid tendency, clinician`s diagnosis and symptoms, MMPI validation scale, and Harris-Lingoes subscale. If the reverse interpretation were valid, low Pa group would differ from middle Pa group in dependent variables and not from high Pa group. Results: HVI cannot discriminate the three group. On the other hand, in the analysis of MMPI validation scale and Harris-Lingoes subscale, the low pa group had higher score on L, K scale than high Pa group. Low Pa group is significantly high in Naivete(Pa3) but low in Persecutory idea(Pa1) and Poignancy(Pa2). That is, patients with low Pa scores were more defensive about their own problems or symptoms and revealed less persecutory idea. But they leaked their covert paranoid tendency through the Naivete subscale. Conclusion: Low score on Pa does indicate paranoid tendency.