Activated glial cells produce many toxic molecules, including cytokines and nitric oxide (NO). There is evidence that excess NO production plays a key role in neuronal cell death. Previous research has demonstrated that cortical glial cells from the left and right cortices of the brain secrete cytokines asymmetrically. However, no evidence to date exists about whether glial cell-produced NO is produced asymmetrically as well. The results of this study show that NO production and inducible NO synthase gene expression are both significantly higher in the right hemisphere-derived mixed glial cell compared with cultures derived from the left.