About 10-30% of patients with non-Hodgkin's lymphoma (NHL) intended to receive high-dose therapy are difficult to mobilise. Damage to the stem cell pool caused by previous chemotherapy may be an important factor in predicting progenitor cell mobilisation. We have analysed associations between chemotherapy score and efficiency of progenitor cell mobilisation in 120 consecutive NHL patients mobilised with intermediate-dose cyclophosphamide (4 g/m(2)) plus G-CSF. The original chemotherapy scoring system proposed by Drake et al was applicable in only 27% of our patients and was not predictive for mobilisation outcome. Therefore we made an improved scoring system for previous chemotherapy by adding new drugs. Altogether, 111 patients (93%) could be scored. Our chemotherapy score showed an inverse correlation with the peak blood CD34(+) count measured after the mobilisation (r=-0.214, P=0.024) and with the number of CD34(+) cells collected (r=-0.234, P=0.02). However, in the receiver operating characteristics curve, no threshold value could be detected for chemotherapy score predicting mobilisation failure. Thus, both the original scoring system as well as our more widely applicable scoring system seem to be of limited value in predicting progenitor cell mobilisation in patients with NHL.