Background: Transfusion emergencies and critical situations require specifically designed devices to simplify and optimize the standard procedures. In addition, matching antigens over and above ABO-Rh-K would be beneficial. Methods: Routine blood samples were collected in four immunohematology centers and tested with the new MDmulticard Basic Extended Phenotype for the simultaneous detection of the Duffy, Kidd, and Ss antigens, according to the principle of the lateral flow. Results were compared with those obtained using routine serology methods. Discrepancies were analyzed by molecular techniques/genotyping. Results: 310 samples were tested (167 donors; 75 patients; 28 subjects with positive direct antiglobulin test (DAT); 15 newborns; 25 previously transfused patients). The 285 samples with non-mixed-field reaction yielded 1,710 antigen results with 8 discrepancies (0.47%) six of which in DAT-positive subjects: three false-positive (Fy^a) for MDmulticard, and two false-positive (Fy^a) plus three false-negative (Fy^b) for the reference methods (MDmulticard PPA for donors/patients/newborns: 99.82%; negative percent agreement: 100%; sensitivity: 100%; specificity: 99.39%, positive predictive value: 99.75%; negative predictive value: 100%). The MDmulticard detected mixed-field in 15 antigen reactions from 13 transfused patients, undetected by the comparative method, with the opposite result in 8 antigens (5 patients). Conclusion: The MDmulticard Basic Extended Phenotype met the criteria prescribed for the testing of donor, patient, DAT-positive, and newborn samples in transfusion laboratory routine.