Sixty-seven glutaraldehyde-processed porcine bioprostheses (PBs), recovered at autopsy or reoperation from 65 patients, were evaluated by roentgenologic and pathologic examination. Seven patients with 8 PBs were younger than 20 years of age. The time interval of function was 2 to 138 months (average 62). Pathologically, 53 explants had signs of intrinsic dysfunction, which was ascribed to calcification in 36 (68%). By x-ray examination, calcific deposits were found in 55 of 67 PBs (82%). The mean duration of function was 70 +/- 32 months in calcified PBs vs 27 +/- 18 months in noncalcified PBs (p less than 0.001). All 26 PBs that had been in place for longer than 6 years were calcified. In 45 PBs the Ca++ deposits were considered severe (mean time of function 76 +/- 32 months) and mild in 10 (mean time of function 44 +/- 22 months) (p less than 0.005). The Ca++ deposits were located at the commissures in 54 PBs (98%), at the body of cusps in 41 (75%), at the free margin in 37 (67%) and at the aortic wall in 37 (67%). When mild, Ca++ deposits involved the commissures in 90% of cases, the body of cusps in 30% and the free margin only in 10%. Forty-seven calcified PBs were mounted on a flexible stent, and 8 had a rigid stent, with an average time of function of 63 +/- 28 and 113 +/- 18 months, respectively (p less than 0.00001). Ca++ dysfunction occurred earlier in the aortic than in the mitral position (59 +/- 19 vs 86 +/- 35 months, p less than 0.05). All the PBs explanted from young patients and 47 of 59 PBs removed from adult patients were calcified, with an average time of function of 50 +/- 21 vs 73 +/- 33 months, respectively (p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)