The transfusion of ABO-compatible blood with blood with an unknown phenotype may result in alloimmunization, particularly in multitransfused patients. Minor blood-group phenotyping and the selection of negative blood for specific antigens reduce post-transfusion complications. With this study, a device called the DROP and READ instrument was developed with a PAD (paper-based device) and various software to phenotype ABO, Rh (D, C, c, E, e), and Mia antigens. EDTA (Ethylene diamine tetra-acetic acid) blood samples were collected from donors, volunteers, and newborns, and were then tested with the DROP and READ instrument according to the lateral flow and RBC agglutination principle. The results were compared with those obtained by using a routine column agglutination test or the tube method. Results: a total of 205 samples were tested (150 from EDTA blood donors, 50 from EDTA blood volunteers, and 5 from the cord blood of newborns). The device yielded 100% accuracy, sensitivity, and specificity, a positive predictive value, and a negative predictive value when interpreting the ABO, Rh (D, C, c, E, e), and Mia antigens. The DROP and READ instrument is developed to automatically interpret the results, and the device provided endpoint results without centrifugation and prevented misinterpretations from human error.