In this study, 86 children (58 initial ALL and 28 children with relapsed disease) were investigated for lung resistance protein (LRP) and multidrug resistance related protein (MRP1)-mRNA expression by semiquantitative RT-PCR. The majority of investigated cases demonstrated variable LRP and MRP1 mRNA expression, when normalized for β -microglobulin expression. LRP and MRP1 mRNA expression may be coordinately regulated, as expression of both transcripts was found to be significantly correlated (p =0.0001). No differences of LRP and MRP expression were observed between initial and relapsed stage patients (LRP: p =0.89 and for MRP: p =0.09 ). The prognostic value of both resistance mechanisms was subjected to Kaplan-Meier analysis for event-free survival. For this analysis the patients were divided into groups with high or low LRP or MRP1 mRNA expression by utilizing the median value as the cut-off point. Overexpression of both resistance mechanisms had no prognostic significance in our retrospective study (log-rank test for LRP: p =0.12 and for MRP1: p =0.95 ), however, patients who showed high LRP expression exhibited a lower tendency of remaining in continuous first remission.