The effects of 14 urease inhibitors on denitrification of nitrate in soil were studied by determining the effects of 1, 10, and 50 μg g‐1soil of each inhibitor on the amounts of nitrate lost and the amounts of nitrite, N2O, and N2produced when samples of soil were incubated anaerobically after treatment with nitrate or with nitrate and mannitol. The inhibitors used were catechol, hydroquinone, 1,4‐benzoquinone, 2,5‐dichloro‐l,4‐benzoquinone, 2,6‐dichloro‐l,4‐benzoquinone, 2,5‐dimethyl‐l,4‐benzoquinone, 2,6‐dimethyl‐1,4‐benzoquinone, sodium‐4‐chloromercuribenzoate, phenylphosphorodiamidate, phosphoric triamide, N‐phenylphosphoric triamide, N‐(diaminophosphinyl)benzeneacetamide, N‐(diamino‐phosphinyl)benzamide, and 4‐fluoro‐N‐(diaminophosphinyl)benzamide.