Background: Suicide risk assessment is a challenging task. Patients may be ambivalent regarding their suicidal intent. Traditional risk assessment tools involve an external examiner, which can affect the validity of the assessment. Implicit association tests may be useful as they do not depend on conscious control. The aim of this study is to validate the Death / Suicide Implicit Association Test (D/S IAT) in the Spanish population. Methods: 75 psychiatric outpatients with a history of suicidal behaviour were administered the D/S IAT and the Columbia Suicide Severity Rating Scale (CSSRS). We determined the predictive validity of the D/S IAT with the occurrence of suicide attempts within the three months of follow-up. The CSSRS was used to calculate the concurrent validity. Results: The Receiver Operating Characteristic analysis revealed an optimal D/S IAT cut-off point of 0.05. Sensitivity was 88.9%, specificity was 93.9%, Positive Predictive Value (PPV) was 66.7%, Negative Predictive Value (NPV) was 98.4%, and overall accuracy was 93.3%. The Area Under the Curve (AUC) was 0.925. We found a positive correlation between the D/S IAT score and the CSSRS score (Pearson correlation = 0.531, p <0.001). Limitations: There were no reported suicide deaths in our sample, so we cannot inform about the performance of the scale in predicting those deaths. Conclusions: The D/S IAT stands out for its high AUC, high specificity and high NPV. Implicit association tests could contribute to suicide risk assessment, particularly when patients are not in a position to disclose their suicide intent.