A proteomics approach was used to study the proteins associated with chinch bug infested corn seedlings. Examination of two-dimensional gels revealed the presence of more than 600 high quality protein spots each from chinch bug-infested and healthy corn seedlings. A total of 31 protein spots was selected for matrix-assisted laser desorption and ionization time-of-flight mass spectrometric analysis. Among the protein spots selected, 13 were from infested plants, 10 from healthy plants, and four each from healthy and infested plants having differential expressions. Peptide mass fingerprinting revealed that each spot analyzed represents a different protein. Thirty-nine percent of the proteins had confirmed identity and the rest were tentatively identified. Among 13 proteins analyzed from infested seedlings most were related to defense, cell rescue, virulence and metabolism. Some of these proteins related to metabolism and protein synthesis were down-regulated in the infested seedlings. All proteins except one from infested corn seedlings seem to be activated in the plant system because of the chinch bug-induced stresses including osmotic, oxidative and acid stresses, and wounding.