The p-halogen derivatives of rifamycin-B anilide are more suitable, as regards stability and crystallinity properties, for crystallographic determination of the structure of rifamycins by X-ray diffraction methods. The complete crystallographic data of rifamycin-B p-iodanilide and p-bromanilide were obtained. The crystals are ortho-rhombic, and the unit cell contains 4 molecules. The stability of the crystals depends on the amount of crystallization solvent; one of the axes and the volume of the unit cell are also correlated with it.