Background: One of the most frequent causes of death is poisoning worldwide. Investigating the causes of mortality due to poisoning profoundly affects making decisions and improving standards for preventing adverse events. Therefore, to better understand this problem and evaluate the causes, this study aimed to determine the risk of suicide using the SAD PERSONS Scale (SPS) criteria and its relationship with the birth month in poisoned patients.Methods: This cross-sectional descriptive-analytic study was conducted on poisoned patients admitted to Khorshid Hospital in Isfahan City, Iran, in 2018. First, the patients’ age, gender, and birth month were recorded. Then, their suicide risk was assessed by SPS.Results: From 2735 referred patients with poisoning, 1839 (67.2%) attempted suicide, and 896(32.8%) cases were poisoned. The Mean±SD SPS score in patients with suicidal attempts was 4.89±1.94, and in the poisoned patients was equal to 2.74±1.46 (P<0.001). There was no significant relationship between suicide and birth month; however, gender (male), age, depression, previous suicidal attempts, ethanol abuse, rational thinking loss, social support lacking, and being unmarried significantly increased the risk of suicide (P<0.01). In addition, the SPS scores ≥5 with a sensitivity of 43.77%, and specificity of 98.44% had an acceptable diagnostic value in identifying the risk of suicide (P<0.0001).Conclusion: As SPS criteria have an appropriate diagnostic value for suicide prediction, it is recommended that these criteria be assessed among individuals with susceptible suicide characteristics (e.g. males, elders, depression, the lack of social support, etc.), to prevent future suicide attempts and appropriate medical-psychological measures.