Using rat paw dextran edema, the antiexudative activity of the complexes of the composition Cu(RCOO)2.nH2O--R represents 2-hydroxy-Y-phenyl: Y = 3 (n = 1,5), Y = 4 (4), Y = 5 (2) or 2-hydroxy-3,6-dimethylphenyl (n = 4)--and of the corresponding uncomplexed acids was assayed. Salicylic and acetylsalicylic acids and their Cu(II) salts were used as standards of comparison. The compounds were administered i.p. in a single dose of 10 mg/kg body weight. In general, the acids were more effective than their copper(II) salts except for the pair m-cresotic acid--Cu(II) complex. Only p-cresotic acid (mean edema reduction 56%) and copper(II) m-cresotate tetrahydrate (43%) exhibited a biological activity comparable to those of salicylic acid (62%) and copper(II) salicylate tetrahydrate (70%). The observed activities of complexes are discussed in relation to their proposed structures.