Fecal corticosterone metabolites and plasma corticosterone in Japanese quail selected for low- or high-plasma corticosterone responses to brief mechanical restraint (low- and high-stress lines), and in a line of unselected quail, were measured in this study. No line differences were observed in baseline plasma corticosterone concentrations, but fecal corticosterone metabolite concentrations and daily fecal corticosterone metabolite production were 20% higher in quail of the high-stress line than in unselected or low-stress quail for males and females living together in group cages (P < 0.05). No differences were observed between lines in corticosterone metabolite concentrations and production for male birds in individual cages. Baseline plasma corticosterone concentrations, fecal corticosterone metabolite concentrations, and production appeared to be higher for males and females in group cages compared with males in individual cages. This difference might have been because of greater corticosterone secretion by male quail living in mixed sex groups than living individually. Correlations between baseline plasma corticosterone concentrations and fecal corticosterone metabolite concentrations in low-stress and high-stress quail, and for all birds combined, were r = 0.521 (P = 0.038), r = 0.604 (P = 0.013), and r = 0.431 (P = 0.002), respectively. The low- and high-stress lines that have been selected for low- and high-corticosterone responses differ in other characteristics, including growth and reproductive performance, and the current results are consistent with the assumption that these other differences are a consequence of greater daily corticosterone secretion in quail of the high-stress line.