The method of inoculation was studied for its effect on the growth and variability of Bacillus thuringiensis H14 266/2-1 when cultivating them in the liquid nutrient medium inoculate with inoculum prepared by different procedures. Optimal conditions of the inoculum preparation are determined. Productivity of the strain when inoculating the medium with the aerial-dry inoculum was studied as compared to the inoculation by the inoculum taken from the mown agar. It is established that selection of the virulent R-form from colonies should serve as a basis for the preparation of the stable morphologically uniform inoculum. The aerial-dried culture of bacilli is shown to be more effective since it is characterized by higher and stable indices of productivity and is more prepared to a long-duration storage than the inoculated agar media. A more rapid transition (by 2-4h) of the culture to the use of the carbon source is marked. The culture of bacilli is different in a higher developmental level: sporulation and crystallization initiate during the first hours of inoculation and by the 24th hour sporulation reaches 100% with the prevailing content of R-form.