Aim: Abortus Imminens is a pregnancy-related disease, the pathophysiology of which has not yet been thoroughly determined. The aim of this study was to investigate possible relations between prolidase (PR) enzyme activity and adenosine deaminase (ADA), glutathione S-transferase (GST) and glutathione reductase (GR) activities in Abortus Imminens patients. Material and Method: Fifty patients with Abortus Imminens were examined in Ipekyolu Women's and Children's Hospital between June 2015 and September 2015. The age range of the patients selected was between 18 and 50. Prolidase (PR) enzyme activity and adenosine deaminase (ADA), glutathione S-transferase(GST) and glutathione reductase (GR) activities were measured in Abortus Imminens serums. Prolidase (PR), adenosine deaminase (ADA), glutathione-S-transferase (GST) and glutathione reductase (GR) activities were determined by spectrophotometry. Results: Glutathione S-transferase and glutathione reductase activities were found to be significantly decreased in Abortus Imminens patients compared to healthy subjects. Discussion: Changes in antioxidant enzyme activities may play a very important role in the pathogenesis of Abortus Imminens. The serum ADA levels can be used as a biochemical marker in Abortus Imminens. This is the first large-scale study in the literature of the relationship between Abortus Imminens and antioxidants.