This relates to agent for detection of genes on pig chromosomes, using hapten-marked cDNA probes which correspond with gene under study. Signal visualization is made by antihapten antibody conjugated with horseradish peroxidase. In subsequent step, the peroxidase serves for production of free tyramide radicals conjugated with fluorophore. These radicals react with variety of compounds around the enzyme. The presented solution enables to localize economically and biomedically important genes simply and specifically on the basis of their cDNA sequence.