Isotopic abundance ratios are excellently suited to probe the origin of solar system matter. We review the recent measurements of the isotopic ratios of the light elements (D/H, 12 C/ 13 C, 16 O/ 18 O, 14 N/ 15 N, 32 S/ 34 S) in cometary dust and gas and discuss briefly their implications. Special emphasis will be put on the determinations and progress performed in the field over the past years thanks to high resolution spectroscopy of cometary comae obtained with the ESO Very Large Telescope. Future perspectives from space missions and ground-based observations with new large and extremely large telescopes operating in the optical, infrared and submillimeter wavelengths will be presented.