This experiment was conducted to evaluate the effects of chromium (chromium picolinate) on performance and plasma concentrations of insulin and corticosterone of laying hens (Ross Brown) under a low ambient temperature (6.9 degrees C). One hundred and twenty laying hens (46 weeks old) were divided into four groups, 30 hens per group. The laying hens were fed either a control diet containing 710.3 p.p.b. chromium or the control diet supplemented with 100, 200 or 400 microg chromium/kg diet. Increasing supplemental chromium increased live weight change (p < or = 0.001, linear) and egg production (p < or = 0.001, linear) and also improved feed efficiency linearly (p < or = 0.001). Live weight change and egg production also had quadratic responses (p < or = 0.001) to increasing chromium supplementation. Plasma insulin concentration increased linearly (p < or = 0.001), whereas corticosterone concentration decreased linearly (p < or = 0.001) as dietary chromium supplementation increased. The results of this study indicate that supplemental dietary chromium, 200 p.p.b. in particular, had a positive effect on performance and increased the plasma insulin concentration of laying hens under cold stress.