Coordination compounds of cobalt, iron, copper and other biologically active metals on the base of α-dioximes have diverse biological properties [1]. The properties of cobalt(III) dioximates with amides of sulfanilic acid were the most extensively studied. It was found that the greatest antibacterial activity manifest those compounds in which the sulfanilamide NH2-C6H4-SO2-NH-R (L) contains various pyridine derivatives, while in the complexes with the general formula [CoX(DioxH)2L] the anions containing the triple bond (NºC-, NºC-S-, NºC-O-, NºC-Se- etc.) are present as X. In agreement with these data, it seems to be useful to obtain the pyrimidinsulfamide complexes of Co(III) with the general formula [Co(N3)(DmgH)2Ln] (=NN ºN being one of the resonance structures for N3 - anion, DmgH- monoanion of dimethylglyoxime), for which the antibacterial activity can be proposed. Three cobalt(III) dimethylglyoximates with pyrimidine derivatives of sulfanilamide were synthesized, in which the radical R varies by the number and location of methoxy groups: formula All novel compounds were characterized by X-ray single crystal diffraction, and physical and chemical properties of these compounds were studied. Complex 1A Complex 1B Complex 2 Complex 3 It was found that in all complexes the metal atom coordinates by four nitrogen atoms of two dimethylglyoxime residues, folded by two intramolecular О– Н×××О H-bonds. One neutral organic molecule L, bound with the central metal atom via nitrogen atom of amino-group and the nitrogen atom of the azide anion complete the coordination environment of Co(III). Thereby, the coordination core of the metal in all complexes is formed by the N6-donor set. In 1–3 the molecular complexes are interlinked through different hydrogen bonds, being N–H×××О, N–H×××N, and О–H×××О, which involve as a H-donor –NH2, and =NH group of the ligand L, as well as the oxime group (1) or water molecule (2). The influence of substituents in the ligand L on the crystal packing is discussed.