The aim of this research has been to determine the degree to which biochemical indices of mood reflect subjective mood. Potential relationships between whole-blood (WB) serotonin (5-hydroxytryptamine, 5-HT) levels as determined by the positive and negative affect schedule (PANAS) have been explored in apparently healthy postmenopausal women (n = 39). Partial correlations indicated that WB 5-HT was positively associated with positive affect (p = 0.03). No association was apparent for negative affect. These findings indicate that WB 5-HT and positive affect are related in postmenopausal women. (c) 2006 Elsevier B.V. All rights reserved.