Abstract Introduction Pretreatment with P2Y12 inhibitors has been widely studied in the context of NSTEMI patients, with varying results. General consensus is that this strategy should be avoided, unless a long wait time is expected before angiography can be performed. However, it is unclear whether this strategy is associated with a reduction in clinical outcomes, or an increase in bleeding events. Purpose To analyze frequency of pretreatment in NSTEMI in our medium, and association with clinical outcomes. Methods We analyzed the results of two Argentinian acute coronary syndrome registries from 2017 and 2022. We explored incidence of pretreatment, and drug used. We evaluated first through univariate analysis the relationship between pretreatment use and a clinical composite outcome of in hospital events: Myocardial infarction + Mortality + In stent thrombosis + post MI angina + Stroke/TIA. We also explored the relationship of pretreatment with bleeding events (BARC 2 or higher). We later conducted a logistic regression with other clinical variables: Age, gender, diabetes, previous bleeding events, previous MI, aspirin use, anticoagulation, killip-kimball scale and ejection fraction. Results 1297 patients were included in the analysis, after excluding STEMI patients, patients with current use of P2Y12 inhibitors at time of event, and patients who did not undergo angiography. 75.6% were men, 25.6% diabetic, 27,1% smokers, 70.3% hypertensive, and 23.1% had a previous acute coronary syndrome. Mean age was 55.3 years old. Mean GRACE score was 113,5 and CRUSADE 23,8. 44% of patients recieved pretreatment, mostly with clopidogrel (93.5%). Patients that recieved pretreatment were more frequently hypertensive (73.8% vs 67%, p=0.01) and had a higher incidence of previous MI (27% vs 19%, p=0.002). GRACE score was significantly lower in patients that were pretreated (111,5 vs 115, p=0.04). Pretreatment use was significantly associated with a higher incidence of the composite clinical outcome, occuring in 10.1% of patients pretreated and in 6.9% of patients not pretreated (OR 1.56 (1.06-2.3) p=0.02. Bleeding events were numerically more frequent with pretreatment (8.7% vs 5.9%), though did not reach statistical significance (OR 1.51 (0.99-2.3) p=0.054). In multivariate analysis, after adjusting for multiple clinical variables, pretreatment was no longer associated with a higher incidence of clinical outcomes, though also not with a lower incidence (OR 1.4 (0.89-2.3) p=0.13). Discussion Pretreatment, mostly with clopidogrel, did not show a relationship with either benefit or harm with regard to ischemic and bleeding outcomes in NSTEMI patients.