Polygalacturonase-inhibiting protein (PGIP) is a cell wall binding protein that can specifically inhibit the activity of fungal polygalacturonase. A PGIP was purified from healthy banana seedlings by a series of column chromatography: ConA affinity column, CM-Sepharose ion exchange column and Sephadex S-100 gel filtration column. The 38.2 ku PGIP was shown as a single band, as determined by SDS-PAGE. Its activity is sensitive to different temperatures. The inhibition of the PGIP to Fusarium oxysporum f.sp.cubense race 4 (Foc4) is higher than its inhibition to Aspergillus niger PG, which suggested the banana PGIP activity might specifically inhibit certain PG.