Although particularly interested in tumor research, investigators in many tumor cytogenetics laboratories cannot afford extensive molecular/interphase cytogenetics studies in addition to routine cytogenetics analyses, primarily because many slides must be stained to examine a few cases using a panel of centromeric probes. Moreover, fluorescence in situ hybridization (FISH) techniques mostly require freshly prepared reagents, such as hybridization mixtures or antibody solutions. These technical requirements are very time-consuming, thus limiting their use in routine screening. We report a significantly economical method for rapid performance of interphase cytogenetics in great numbers of cases. The major advantage if its superior efficiency: up to 16 different probes may be used on one single slide. Moreover, the method is significantly cheaper than other techniques owing to minimal probe consumption. The technique is also best suited if great numbers of new probes, e.g., polymerase chain reaction (PCR)-generated YAC-probes [5], must be tested for their applicability in FISH.