Objectives. Type D personality was identified as an important factor that can explain the differences in clinical outcomes in various diseases. The aim of this study is to clarify the relationships between Type D personality and clinical status of patients with Ankylosing Spondylitis (AS).Methods. The scores of the Bath Ankylosing Spondylitis Disease Activity Index (BASDAI), Ankylosing Spondylitis Disease Activity Score (ASDAS)-C-reactive protein (CRP), and erythrocyte sedimentation rate (ESR), the Bath Ankylosing Spondylitis Functional Index (BASFI), the 36-Item Short-Form Health Survey (SF-36), and 14-item Type D Scale (DS-14) were noted.Results. We found significantly higher levels of the BASDAI, the BASFI, and the SF-36 mental subscale scores in patients with Type D personalities compared to those who were Non-Type D (p < 0.05). The total DS-14 scores were found to be correlated with the scores of physical and mental subscales of SF-36, the BASDAI, the BASFI, ASDAS-CRP, and ESR (p < 0.05). In logistic regression analysis, the occurrence of Type D personality was found to be an independent predictor for disease activity of AS due to BASDAI and ASDAS-ESR (p = 0.016, OR, 95% CI = 2.98,1.23-7.22; p = 0.022, OR, 95% CI = 2.78,1.16-6.63 respectively).Conclusions. Patients may over-rate self-reported measurements such as the BASDAI, BASFI, and SF-36 related to their interpersonal characteristics. Therefore, including the Type D personality, which is a stable construct in evaluating AS patients with brief and valid DS-14, may be noteworthy.