A rapid and simplified fluorescence in situ hybridization (FISH) technique for the detection of human chromosome-specific centromeric probes is described. Using chromosomes 1-, 4-, 11- and Y-specific fluorescence-labeled probes, the modified, or quick-FISH technique, was compared to two conventional FISH methods. The modified FISH technique detected human chromosomes without sacrificing sensitivity or signal quality in both fresh-frozen and paraffin-embedded tissue sections. Further studies demonstrated that this technique can be used with simultaneous application of dual-color probes. This novel technique offers the advantages of being simpler to perform and faster than conventional techniques. The quick-FISH technique can be substituted for any sensitive conventional FISH method for molecular cytogenetic analysis in fresh, fresh-frozen or paraffin-embedded tissues.