This experiment was carried out to compare the effect of ammonia gas and aqueous ammonia as well as the effect of levels (2.5% or 3.5%) on the digestibility of the barley straw by sheep. The results obtained are as follows: 1) There were no significantly different among treatments in the digestibility of dry matter, organic matter and nitrogen of ammonia treated barley straw 2) The degradation of dry matter of barley straw was increased from 40.66% to 60.26% by ammonia treatment after incubation of 72 hours in the rumen. 3) The voluntary feed intake of ammoniated barley straw in the sheep was shown similar pattern among the treatments regardless of the type and the levels of ammonia application. This result of the experiment indicates that the nutritive value of barley straw could be increased by the use of 2.5% ammonia gas or aqueous ammonia