A reciprocal translocation, t(3;12)(q27;q13), was found as the sole karyotypic abnormality in an intramuscular lipoma. The morphology of the derivative 3q+ was strongly reminiscent of the large ring marker we have previously described in three other lipomas, indicating a pathway through which the rings may have arisen. These data, combined with the previous preliminary report by Turc-Carel et al. of a similar t(3;12) in another lipoma strongly suggest that this rearrangement may be a characteristic cytogenetic marker in benign lipogenic tumors.