By bacterial leaching of bulk concentrates of complex sulphide ores, acid leachates are produced which besides valuable metals as zinc and copper also contain high concentrations of impurities such as iron and arsenic, In order to evaluate the proper conditions for removal of iron and arsenic by precipitation as ferric arsenate with limestone, a series of batch precipitation experiments was conducted at various pH values in the range 2-6. The results from these tests showed that pentavalent arsenic and ferric iron can be effectively precipitated to low concentrations when the precipitation is carried out at pH 3 without causing losses of zinc; however, the ferrous iron, approximately 1 g/l, remains in solution. When the precipitation is carried out at pH above 3 in order to oxidize ferrous iron, unacceptable high zinc losses were obtained.