Laser ablation (LA)-inductively coupled plasmamass spectrometry (ICP-MS) has become one of the most important methods for in situ trace elemental and isotopic analysis in geochemistry, cosmochemistry and environmental research. For these purposes, different kinds of mass spectrometers and lasers are used, which are presented in this paper. One of the most useful LA-ICPMS instruments is the combination of a single-collector sector field mass spectrometer with Nd:YAG laser ablation systems (193 nm and 213 nm wavelengths, respectively). This design used in the MPI Mainz laboratory is described in detail in this paper. Data optimization techniques including diverse correction procedures are also discussed. To demonstrate the power of LA-ICPMS, several applications of trace elemental and isotopic analysis are presented, such as investigations of reference materials, trace element analysis in Hawaiian basalts, Martian meteorites, biological spicules and corals, as well as Pb and Sr isotope measurements of melt inclusions and Ca-Al rich inclusions of carbonaceous chondrites.