We examined the conservation of hot regions in protein-protein interaction in evolution for the first time. We studied sequence conservation of hot regions in different species annotated in the database ASEdb, applying the BLOSUM matrix to construct conservation scoring function of hot regions. The experimental results showed that there is high correlation of conservation between hot regions in different species. We further tested the conservation of hot regions in different species annotated in the latest SKEMPI database using the same method. Our experimental results suggest that there is obvious conservation in hot regions.