The enzyme-linked immunospot (ELISPOT) assay due to its high sensitivity is widely used for the detection of secreted cytokines at the single-cell level. Quality of staining is the key for accurate detection of spots and their subsequent quantification in ELISPOT assays. A simple technique employing regular aluminum foil has been developed to improve the quality of staining. In plates wrapped with aluminum foil non-specific background staining and artifacts were reduced or abolished. Application of aluminum foil allowed better contrast of specific spots as well as their uniform distribution across the filter membrane. This technique provides an inexpensive and reliable tool for large-volume immune system cells screening by improving well-to-well reproducibility in ELISPOT plates.