BACKGROUND: Depression is associated with an increased risk for cardiac morbidity and mortality in patients with coronary heart disease (CHD). Cardiac autonomic nervous system (ANS) dysregulation, proinflammatory processes, and procoagulant processes have been suggested as possible explanations. METHODS: Heart rate variability (HRV), an indicator of cardiac autonomic regulation, and markers of inflammation [C-reactive protein (CRP), interleukin-6 (IL-6), tumor necrosis factor-alpha (TNF-alpha)] and coagulation (fibrinogen) were assessed in 44 depressed patients with CHD. RESULTS: Moderate, negative correlations were found between fibrinogen and four measures of HRV. IL-6 also negatively correlated with one measure of HRV (total power) and was marginally related to two others (very low frequency and low frequency power). Neither CRP nor TNF-alpha was significantly related to any measure of HRV. CONCLUSIONS: The finding that fibrinogen and IL-6 are moderately related to HRV suggests a link between these factors in depressed CHD patients. The relationship between ANS function and inflammatory and coagulant processes should be investigated in larger mechanistic studies of depression and cardiac morbidity and mortality.