ABSTRACT A mesenchymal hamartoma of the liver (MHL) from a 20-month-old girl was studied cytogenetically. The karyotype was 46,XX,inv(19)(p13q13.4)[38], and fluorescence in situ hybridization using bacterial artificial chromosome probes refined the breakpoints to 19p13.11 and the subtelomeric region of 19q. This is the first report of inversion (19) in MHL, and the q-arm breakpoint is different from that reported previously in other rearrangements.