Four patients with hepatosplenic T gamma/delta lymphoma, a rare but distinct entity of peripheral T cell lymphoma, are reported on. In each case, cytogenetic studies showed the presence of an Isochromosome 7q and a trisomy 8. A few chromosome studies have previously been reported in this lymphoma subtype but comparison with these published cases confirms that isochromosome 7q and trisomy 8 are primary, non-random chromosomal abnormalities in hepatosplenic T gamma/delta lymphoma.