OBJECTIVE. Various types of prostheses have been used for combined diseases of the aortic root and ascending aorta. METHODS: All Bentall-type operations (n=64) between 1996 and 2005 were retrospectively studied, comparing different types of prosthesis in the aortic position. The patients were 29-87 years old (mean 59.5 +/- 14.0 years) and included 47 men and 17 women. Mechanical valves, stentless bioprostheses (Freestyle), stented bioprostheses, and a homograft were used in 31, 29, 3, and I patients, respectively. Early results, especially hemodynamics, were analyzed among two groups: mechanical valve group (M-group) and Freestyle group (F-group). RESULTS: The average age was significantly higher in the F-group (62.8 +/- 12.7 years) than in the M-group (54.9 +/- 14.0 years) (P = 0.025). The implanted valve was significantly larger in the F-group (26.0 +/- 2.3 mm) than in the M-group (23.5 +/- 2.1mm) (P = 0.000). The estimated effective orifice area of the prosthesis was significantly larger in the F-group (2.23 +/- 0.38 cm2) than in the M-group (1.84 +/- 0.49 cm2) (P = 0.001). The pressure gradient across the prosthesis was significantly lower in the F-group (18.6 +/- 5.5 mmHg) than in the M-group (25.4 +/- 7.6 mmHg) (P = 0.001). CONCLUSION: The Bentall-type procedure using the Freestyle valve has an advantage regarding hemodynamics compared to the procedure employing mechanical prostheses.