Abnormalities of the short arm of chromosome 12 have been detected in a wide variety of hematopoietic disorders. Seven cases of non-Hodgkin's lymphoma (NHL) are reported with various rearrangements involving bands 12p13 or 12p11, associated with other chromosome changes. A review of the literature confirms that rearrangements of 12p, mainly at band 12p13, are nonrandom chromosomal abnormalities in all subtypes of NHL, as in other malignant blood disorders. No common translocation could, however, be detected, and 12p abnormalities may be considered as secondary chromosomal events. Most of the 12p rearrangements involving translocation of genetic material of unknown origin, suggest that they result in loss of 12p segment.