Chromosomal segregational defects are commonly observed in cancer cells and are an important source of genetic instability. It is currently unknown whether these mitotic defects are the result of a subpopulation of defective cells or reflect characteristics of the population of cells as a whole. In this study, we compared chromosomal segregational defects in two oral squamous cell carcinoma cell lines and five single-cell clones from each of those cell lines. We used immunofluorescence microscopy to quantitate the occurrence of multipolar metaphase spindles, lagging chromosomes at metaphase and anaphase, and anaphase bridges. We conclude that chromosome segregational defects in these cancer cell lines represent an intrinsic and inherited tendency toward segregational defects in the general cell population, rather than the existence of a subpopulation of cells with segregational defects.