Trends in the use of bioprosthetic versus mechanical valves for AVR and MVR were assessed using a California-based surgical population from 1996-2013.  During this period the use of bioprosthetic devices increased from 12% to 52% for AVR and from 17% to 54% for MVR.  Bioprostheses were associated with substantially increased 15-year mortality in younger patients and had a higher rate of reoperation.  Mechanical valves were associated with higher rates of bleeding and stroke.