[en] This paper focuses on the advancements made in open-hole nuclear logging in recent years and the improvements in interpretation which are ensuing. Spectral Gamma Ray logs are improving the determination of clay content and assisting in clay typing. Secondary applications are fracture detection, source rock identification and quite recently, lithology indication. Density logging is undergoing a major transition to a new generation of spectral tools. The photoelectric (P/sub e/) curve provides a significant advance in lithology identification. By contrast Neutron log development (with encapsulate sources) is on a plateau. Field tests of a new-generation dual-porosity tool have been inconclusive. Simplified interpretation of Neutron logs and better standoff correction is needed. Nonetheless, combination of Spectral Density, Compensated Neutron and Spectral Gamma Ray data is becoming the basis for much-improved lithology-porosity determination. Methods utilizing P/sub maa/ vs U/sub maa/ and P/sub e/ vs Th/K crossplots are in commercial use. Advancements in the future can be expected from the use of neutron-gamma spectroscopy tools, initially with low resolution detectors, now commercially available, and later with high resolution detectors, still experimental. These promise, for example, a lithology-porosity solution in barite-loaded mud or rugose holes, where the Spectral Density is deficient