A monitoring program for Heliothis virescens adults was established in 1987 by PEG-US. Adults were collected from monitoring sites across the cotton belt and evaluated for tolerance to cypermethrin using an adult vial testing technique. In areas where monitoring was established throughout the cotton growing season, tolerance levels increased in late summer and then declined. The highest levels of tolerance were found in sites located in Texas. From data collected in 1987 it was difficult to relate results from the adult vial tests to field performance of cypermethrin. The monitoring program will continue in 1988 with increased emphasis on seasonal changes in tolerance, especially in those areas where high levels of tolerance were indicated in 1987.