We describe four patients with a mature T-cell disorder. These four sp
ecific entities belong to a group formerly called ''T-cell chronic lym
phocytic leukaemia'' (T-CLL). Nowadays we understand that these chroni
c T-cell lymphoproliferative disorders consist of four different entit
ies. They stand out as well-described and separate disorders on the ba
sis of their clinical, immunophenotypic and cytogenetic properties. Un
fortunately, the majority of patients have a bad response to chemother
apy. The purine analogs may offer a better prognosis for some patients
.