It has been assumed that all of the nitrogen in oil shale from the Green River Formation is present as organic nitrogen and that the nitrogen in spent shale from retorting is present in the char or coke. In fact, from 41 to 84 percent of the nitrogen is present as ammonium fixed within silicate minerals in five samples of raw oil shale and between 46 and 69 percent of the nitrogen is similarly fixed in two samples of spent shale. Both organic nitrogen and fixed ammonium-nitrogen are lost during retorting by the Fischer assay procedure; the loss of organic nitrogen is greater.