Abstract: Objective To investigate the in vitro inhibition effect of the rabbit serum immunized with P.falciparum chimeric protein on the parasites by lactate dehydrogenase （LDH） method. Methods Sera of rabbits immunized with P.falciparum chimeric protein were used as test sample， with an initial parasitemia of (0.4±0.1)% and 2% hematocrit suspension. After 40-42 h of cultivation, LDH assay and a traditional microscopical method were applied to obtain the parasite inhibition rate and infection rate of erythrocytes. Results Sera of rabbits immunized with the protein showed a strong in vitro inhibition effect on P.falciparum. There was no significant difference of inhibition rates detected by the two methods (97% and 100% respectively) （P>0.05）. Conclusion The LDH method applied in the in vitro inhibition assay for P. falciparum seems simple, reliable and has generated a satisfactory result.

Key words: Plasmodium falciparum, In vitro inhibition, Lactate dehydrogenase