[en] The application of logging in geological survey of the North Bohemian Brown Coal Basin results in considerable savings because it allows replacing core boreholes with less costly coreless boreholes. Originally, electrologging had been used but after the introduction of radioactivity logging methods, especially gamma-gamma logging, the quantitative interpretation of electrologging results was discontinued. Currently, two logging sets are used, ie., the Hungarian-made K 13A and the US-made P-250 allowing resistance measurements, current logging, gamma logging, gamma-gamma logging in density modification, neutron-neutron logging, resistivimetry, thermogradient and differential temperature recording, flow metering, well cavity metering, and inclinometry. Gamma-gamma logging yields good results for determining bulk density and coal ash content with an accuracy of about 5%. Neutron-neutron logging is being introduced for the quantitative interpretation of porosity. (Ha)