Research in the area of Persian Gulf War Unexplained Illnesses (PGWUI) is heavily dependent on self-reports of exposures. The Portland Environmental Hazards Research Center (PEHRC) conducted a population-based case-control study utilizing techniques to measure the magnitude of potential error in self-reports of exposure. While it is impossible to verify most exposures in the Persian Gulf War (PGW), results of our study reveal significant overreporting of exposures that can be verified based on the time period served in the Persian Gulf. Test-retest reliability estimates indicate inconsistency in frequency and rate of self-reported exposures during the PGW. Unexplained illness in PGW veterans has received much political and scientific attention. Self-reported exposures in surveys returned preceding and following media reports on particular exposure such as nerve gas or pesticides are presented. These results are useful in the interpretation of findings related to the PGWUI and in the design of future investigations.