The PRimed IN Situ synthesis is a method for rapid identification of chromosomes in metaphase or interphase on cytological preparations and frozen tissue sections, using oligonucleotide primers derived from chromosome specific subsets of repeated DNA families. PRINS technique is an alternative to fluorescence in situ hybridization, as sensitive as FISH but faster and more specific. This technique is potentially of great interest for pathologists involved in transplantation pathology or cytogenetic interphasic oncology.