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 Nitrogen release patterns from seven leguminous trees were determined from 8-week laboratory incubations. The quantities of extractable NH₄ ⁺-N and NO₃ ^– released to the soil to which the leaves had been applied was determined at weekly intervals and was related to the initial N, polyphenol, and lignin concentration of the leaves. Cumulative N mineralized was not correlated to initial N, soluble polyphenol and insoluble tannin concentrations, but was correlated to lignin and neutral detergent fibre N (NDF-N) concentrations. The ratios of NDF-N : N (r=0.68 at P<0.05), soluble polyphenol : N (r=0.70 at P<0.05) and (lignin+polyphenol) : N (r=0.75 at P<0.05) were negatively correlated with N release. Total polyphenol content was not a useful predictor of N release, but the reactivity of the polyphenols as measured by their protein-binding capacity can be a useful predictor. In addition to measuring …