Forty eight crossbred pigs (17.0 kg) were assigned to one of three dietary treatments in a 3 x 2 factorial design experiment. The control diet was based on barley and soyabean meal while the two experimental diets contained 60% of either high or low viscosity rye. Pigs fed either of the rye-based diets had significantly higher (P<0.05) digestibility coefficients for dry matter and gross energy than did pigs fed barley. The digestibility coefficients for dry matter, crude protein and gross energy were numerically higher for pigs fed the low viscosity rye than the high viscosity rye (P>0.05). Pigs fed either of the rye-based diets consumed significantly less feed and gained weight at a slower rate than did pigs fed the barley-based diet. The pigs fed the low viscosity rye gained 8.7% faster and consumed 9% more feed than pigs fed the high viscosity diet but these differences did not reach statistical significance (P>0.05). The overall results indicate that selection to reduce the viscosity of rye only slightly improved the nutritive value of rye for pigs. The magnitude of the improvement indicates that a substantial reduction in viscosity is necessary in order to observe a measurable difference in pig performance.