Abstract: 　AIM:To determine the sensitivity of P.falciparum to chloroquine,amodiaquine,piperaquine,mefloquine and quinine in Yunnan Province of China in 1992～1995.METHODS:Rieckmanns in vitro microtechnigue was used. The sensitivity of P.falciparum was tested to the above mentioned antimalarials.RESULTS: The resistance rates of isolates of P.falciparum from the south, southeast and the west part of Yunnan to chloroquine and amodiaquine were 96 7%(29/30),78 9%(30/38),95 7%(22/23) and 100%(30/30),85 3%(29/34),8/9, respectively,with their corresponding ID 50 of 125 nmol/L,136 nmol/L and 176 nmol/L, and 52 nmol/L,64 nmol/L and 72 nmol/L,respectively.All the isolates were sensitive to quinine and their ID 50 were 480 nmol/L ,352 nmol/L,608 nmol/L ,respectively. The resistance rates of P.falciparum from the south part and southeast part of Yunnan to piperaquine were 96 4%(27/29),72 9 (27/37),respectively,their ID 50 were 320 nmol/L and 228nmol/L;all the cases were sensitive to mefloqine,their ID 50 were 68 nmol/L and 88 nmol/L. CONCLUSION: P.falciparum generally produces resistance to chloroquine, amodiaquine and piperaquine in Yunnan Province; the degree of resistance to chloroquine of P.falciparum from the west part of Yunnan were higher than the P.falciparum from the southeast part of Yunnan;all the isolates were sensitive to mefloquine and quinine in this region.

Key words: Plasmodium falciparum, in vitro, microtechnique, chloroquine, amodiaquine, piperaquine, mefloquinine, quinine