OBJECTIVE: To validate a new assay for lupus anticoagulant (LA) that employs crude diluted venom of Bothrops atrox (dBat) comparing it with four phospholipid - dependent assays. MATERIAL AND METHODS: Citrated serum samples from 70 inpatients clinically diagnosed as having SLE, primary antiphospholipid syndrome (PAPS), thrombosis/embolism or suspected thrombosis from the Hospital Guillermo Almenara Irigoyen over 12 months, were assayed. dRVVT was used as comparative test for reference values. RESULTS: 30 samples were positive to dBat and dRVVT tests plus at least another one of the remain assays; 27 samples had negative results in all assays and there were 13 in which dBat results had not concordance with dRVVT results (p>0,05). 47,8% of SLE, 71,4% of PAPS, 75% of thrombosis and 47,8% of suspected thrombosis cases were LA (+). CONCLUSIONS: The high concordance between dBat and dRVVT re...