The attachment style is one of the significant factors affecting the grief process and complicated grief. This study aims to research the relation between the factors determining the sociodemographic features, the reactions of grief, the suicidal behaviour and the grief process on the patients who are followed and treated with the complicated grief diagnosis and the features of attachment. The study includes 45 patients directed to a therapy unit and meet the criterions of complicated grief diagnosis. 33 of those patients have completed their treatment. Sociodemographic and clinical data form applied to the patients at the beginning, to evaluate for comorbid psychiatric disorders structured clinical interview for DSM-IV axis I disorders, adult attachment style questionnaire (AASQ), grief scale, hamilton rating scale for depression (HDRS), suicide behaviors questionnaire (SBQ), suicide probability scale (SPS), experiences in close relationships inventory (ECRI) are applied on the participants and compared the results of the scales prior to and following the treatment. In the dimensional evaluation of attachment, ECRI avoidance score is high over the patients diagnosed with comorbid psychiatric disorders with complicated grief. During the first application of the treatment, while evaluating the attachment categorically, in the complicated grief patients attached with avoidance grief scale, behavioural base scale and SPS negative self base scale are higher compared to the group whose HDRS scores attached with secure. The results show that in complicated grief cases the avoidance attachment is both dimensionally and categorically related with the strength of grief reaction and additional psychiatric problems.