The ammoniation of wheat straw by urea in a stack method was investigated and compared to urea supplemented and untreated straw in an intake and in vivo digestibility trial. Ammoniation and supplementation significantly (P ≤ 0,01) improved the mean daily consumption of wheat straw by 46,7 and 35,6% respectively. The improvement of 8,1% in the voluntary intake of ammoniated wheat straw compared to urea supplemented wheat straw was not significant. Apparent digestibility of OM, OM, CWC, ADF and hemicellulose was significantly (P ≤ 0,01) improved by 17,5; 15,1; 24,1; 14,3 and 39,2% respectively, when ammoniated straw was compared to untreated straw. Corresponding improvements of 10,0; 8,4; 17,8; 8,7 and 29,2% were obtained when ammoniated straw was compared to urea supplemented straw. All these differences were significant at least at P ≤ 0,05. Similarly, urea supplementation tended to increase the digestibility of the above-mentioned fractions marginally. Both ammoniation and urea supplementation of wheat straw significantly (P ≤ 0,01) improved the apparent digestibility of CP as well as the N-balance. The apparent digestibility of CP of ammoniated wheat straw was significantly (P ≤ 0,01) reduced by 22,1 % compared to urea supplemented wheat straw. The N-balance of ammoniated wheat straw, on the other hand, was marginally higher than that of urea supplemented wheat straw, mainly owing to a higher level of urinary N-excretion observed on the latter treatment.