Some recent reports suggested that elderly and female patients did not benefit from implantation of the second internal thoracic artery (ITA) during coronary artery bypass surgery (CABG). Macrophages, among other cells, were described to be involved in both atherosclerosis and aortocoronary grafts failure. The aim of the study was to examine the age and gender association with different distribution of CD68+ cells within the layers of ITA wall. This study involved 158 consecutive patients (95 male and 63 female), with the mean age of 64.5±9.5 years, who underwent elective CABG procedures. During surgery, the surplus distal segments of ITA were harvested for immunohistochemical analysis. The number and distribution of CD68+ cells was calculated and plotted against the age and gender of the study participants. CD68+ cells were present in all of the harvested ITA fragments (median 44), more in women (55) than in men (42) (p less than 0.001). However, this difference was of statistical significance exclusively in the tunica intima. Approximately 70% of macrophages were found in the tunica adventitia. The total number of CD68+ cells the in arterial wall as well as in the tunica intima and adventitia correlated positively with the age of patients (r=0.544, r=501 and r=0.462, respectively). The lack of significant advantages of the use of two thoracic arteries, in elderly patients and women, might have resulted from the larger population of CD68+ cells in their walls, especially the tunica intima. However, this result from immunohistochemical analysis needs validation in long-term clinical research on a larger cohort of patients.