OBJECTIVE Pre-transfusion antibody screening requires the detection and identification of immunoglobulin G (IgG) antibodies against red blood cells (RBCs). Using the indirect antiglobulin test (IAT), plasma-RBC solutions are incubated at 37°C in gel cards, typically by heating block technology. Here, we apply the newly developed laser incubation method to detect RBC alloantibodies in the plasma from human donors. METHODS Donated human plasma samples (N = 128) containing clinically significant IgG antibodies directed against Rh (D, C, c, Cw and E), Kell (K and Kpa ), Duffy (Fya and Fyb ), Kidd (Jka ) and MNS (S) blood group system antigens were tested by the indirect antiglobulin test (IAT). Samples were heated to 37°C by infrared laser (980 nm) for incubations of up to 5 min. Samples were also incubated in a heating block for comparison. RESULTS When heating by laser, the presence of an alloantibody is detected after only a 1-min incubation for 96% of samples. No samples required longer than 3 min of laser incubation in order to detect the antibody. For all samples, incubation by laser gave the same or stronger result within 5 min. No samples required longer than 5 min to achieve an equivalent result to that of the 5-min heating block incubation. The laser was not found to damage cells or antibodies. CONCLUSIONS Laser incubation provides comparable results in shorter time frames than the heating block. Laser incubation can rapidly detect even very weak antibodies.