In-situ analysis of sulfur and chlorine in geological materials is typically conducted by electron probe micro-analysis or secondary-ion mass spectrometry. Both of these methods require a homogeneous material that is exposed at the surface, which is commonly not the case for silicate melt inclusions. To overcome this issue the accuracy and precision of sulfur and chlorine quantification by laser-ablation inductively-coupled-plasma (quadrupole) mass spectrometry (LA-ICP-MS) were investigated for melt inclusions and also for glasses and minerals. Samples with known sulfur and/or chlorine concentrations were analyzed using suitable external standards. The main limitation for chlorine and sulfur quantification in geological materials by LA-ICP-MS is a contamination effect resulting in excess Cl and S signals during ablation of any material. This contamination results from the mobilization of chlorine and sulfur impurities attached to the walls of the sample chamber and the gas transport tubes. In the case of Cl accurate results can be obtained for Cl concentrations of few hundred of ppm after applying a simple correction formula that relates the magnitude of the excess Cl signal to the quantity of produced aerosol, which is approximated by sensitivity. In the case of S the application of a similar correction formula does not suffice, and a second correction formula that relates the calculated sulfur content to the actual sulfur content needs to be applied. The combined approach allows accurate quantification of S in minerals and glasses down to a concentration of ~600 μg/g. For unexposed silicate melt inclusions the numerical host correction automatically removes the excess Cl related to the amount of produced aerosol, hence Cl concentrations turn out accurate without any correction. Due to counting statistics and uncertainties in the host correction a minimum melt inclusion size of 30 μm is required to accurately quantify Cl in melt inclusions containing ~1500 μg/g Cl. Sulfur concentrations, on the other hand, can be accurately quantified down to 700 μg/g even in small (15 μm) melt inclusions. In summary, chlorine and sulfur can be accurately and precisely quantified by LA-ICP-MS in glasses, minerals, and melt inclusions down to a concentrations of several hundreds of μg/g, provided that an ICP-MS instrument with relatively low background on Cl and S is available and that instrument-specific correction equations are established on a set of samples with known Cl and S contents.