Circulating glucocorticoids have not been shown in a longitudinal manner to be consistent within an individual in a longitudinal manner. In 88 male mice were sampled with a baseline and stress glucocorticoid levels and exploratory were repeatedly measured over nine months. There were significant differences in young vs. old glucocorticoid levels, and individual glucocorticoid levels were relatively consistent over time (I.e. trait-like). However, there was no significant relationship between individual behavior and glucocorticoid levels.