Polymorphonuclear neutrophils (PNN) chemiluminescence results from the luminescence emission in oxidative reactions during phagocytosis. This activity is easily detectable and measurable using a luminometer. PNN luminescence allows precociously the evaluation of the end of the aplasia. We have analysed PNN luminescence emission stimulated by latex beads in 69 patients with hemopathies after 72 aplasias following autologous bone marrow transplantation (9 pts), allogeneic bone marrow transplantation (26 pts) and acute myeloblastic leukemia (AML) induction chemotherapies (37 pts). Luminescence emission was measured in whole blood using a luminometer before, during and after aplasia and was compared to PNN manual count. Chemiluminescence measurement is a simple and reproductable method. Its allows more earlier than the PNN blood count the detection of PNN recovery: chemiluminescence nadir is reached on average on the fourth day of aplasia and correspond to the value procured by sample tubes without PNN. The onset of the chemiluminescence increasing is definite by the doubling of the nadir value. It is reached on average on the fourteenth day of aplasia. It precedes 3.5 days and 10.5 days a total PNN count > or = 0.1 x 10 9/1 and > or = 0.5 x 10 9/1 respectively, in the 72 aplasias. In autologous and allogeneic bone marrow transplantation, chemiluminescence increasing precedes at least PNN > or = 0.1 x 10 9/1 of 4.6 days whereas in AML induction chemotherapies, the advantage is only 1.5 day (p = 0.0078). The chemiluminescence could be considered as an additional tool in daily management of sustained aplasia.