Plant cytogenetics has continued to flourish and make essential contributions to genomics projects by delineating marker order, defining contig gaps and revealing genome rearrangements. Here we review the field of plant cytogenetics from its conception through the eras of molecular biology and genomics. Significant advances in chromosome preparation, such as extended fiber-FISH, have greatly increased the axial resolution limits, while imaging and signal amplification technologies have improved our ability to detect small gene-sized probes. Combinations of traditional FISH technologies with chromatin immunocytochemistry serve to broaden the ability of plant cytogenetics to shed light on genome structure and organization. These advances are described, together with selected examples that illustrate the power of plant cytogenetics in guiding genome projects.