The distribution and stable isotopic composition of nitrogen released at low temperatures from the ALH 84001 Martian meteorite have been appraised. The results demonstrate an apparently complex geochemistry of the element, with at least three, and possibly four, separate components present. While the isotopic composition of most of the nitrogen is within the range of typical terrestrial materials (and thus is probably contamination), nitrogen in the balance of the material has a very different Δ15N value. Isotopically light nitrogen (component N2; 2.2 ppm with Δ15N~-30? and C/N~6) is released when a carbonaceous phase combusts below 300 ¿C. Since amino acids and nucleic acid bases have C/N~2--3, the host phase of N2 could be from a mixture of such compounds. The associated nitrogen isotopic composition is very different from terrestrial contaminants; while this is suggestive of a Martian origin for the components, it is difficult to reconcile without advocating formation under special conditions. ¿ 1999 American Geophysical Union