Polygalacturonase inhibitory protein (PGIP) was extracted from Shinli pear tissue, purified and partially characterized. Extraction was carried out at 4oC with a high ionic strength extraction buffer. After dialysis and concentration by ultrafiltration, the extract was chromatographed on size-exclusion chromatography (S-100), and its active fractions were applied on concanavalin A-Sepharose. The PGIP activity was bound by the lectin, and then eluted using 1M α-methyl mannopyranoside, resulting in a 18-fold purification of the PGIP and demonstrating its glycoprotein nature. The following ion-exchange chromatography gave a PGIP that was 360-fold purified relative to the initial tissue extract, and having a 45kDa molecular weight, as estimated by SDS-PAGE electrophoresis. PGIP inhibitory activity was tested against A. niger, C. acutatum and B. cinerea. The radial diffusion and reducing sugar assays showed that PGIP inhibitory to three PGs was affected by pH. In vivo tests revealed that PGIP inhibited three polygalacturonase from all three fungi. Heated for 20 min at 85oC, the inhibitory activity of PGIP was reduced by 85-90%, and it was completely suppressed after being heated at 100oC for 20 min.