Fibrous diets have not proven effective in reducing hunger in pregnant sows except just after feeding. We therefore tested if free access to straw alone, or in combination with a fibrous diet, reduced hunger. Two blocks of 15 pregnant sows housed in groups of 3 were allocated to limited amounts of chopped straw or free access to long straw. The experimental period (week 1 to 9 of pregnancy) were divided into two 4-week-periods. During one period sows within a group were fed a control diet (wheat/barley; 17.5 % fibre) while during the other period they were fed a fibrous diet containing 35 % fibre from sugar beat pulp. Both diets were offered restrictively at 21.62MJ net energy/day. Sows were fed twice daily at 0800 and 1500. Towards the end of each period hunger was assessed using operant conditioning. The operant response was lever pressing for a food reward (27 g per reward) on a progressive ratio that increased 5 presses for every second reward. Sows were tested in a balanced design at 0700, 0900, 1200 and 1900 hours. The data was analysed using variance component analysis. There was no effect of free access to long straw compared to control straw (maximum level of responding: 76 vs. 78 (SE 5.0)). The level of responding was significantly higher during tests at 0700 compared to tests at 0900, 1200 and 1900 (P=0.03). The level of responding at 0900 was higher during control fed periods compared to fibre fed periods (79 vs. 67 ( 5.6 ), P=0.03) and tended to be higher at 1200 for control fed periods compared to fibre fed periods (80 vs. 69 (5.6), P=0.06). In conclusion, free access to straw did not improve satiety neither in control nor in fibre fed sows. The fibrous diet reduced hunger just after feeding.