The purpose of this thesis constituted the optimization of the drill and blast work applied in drifts in the underground marble mine Kristallina, by Omya S.p.A., in Vipiteno, Italy. In order to lower drift development costs, especially with respect to explosives and amount of fines produced, the high specific charge concentration as well as the high specific borehole amount were assessed. Regarding the specific charge concentration a decreased borehole diameter turned out to be technically feasable and has led to an economical improvement. Concerning a reduction of the high specific borehole amount, experimental tests on the blastability (Critical Burden Method) both in model and large scale tests have been performed. For practical mining, it was essential to find a geometric arrangement for boreholes (burdens and spacings) before the critical burden is reached at which the specific charge, which is in direct correlation to the burden, shows a minimum and therefore has a positive influence on the size distribution of the blasted rock. The newly developed drilling and blasting pattern was then realized in a full round blast and both a technical and economical comparison of the current and the new drilling and blasting patterns applied in drifts was drawn.