Despite their different mechanism of action, the antitumor efficacy of overall anticancer therapies would depend not only on their antitumor cytotoxic activity, but also on the immune biological response of cancer patients, which is the result of interactions between immunostimulatory and immunosuppressive events. Today, it is known that the anticancer immunity is mainly depending on T helper (TH) (CD4+) and dendritic cells, whereas it inhibited by the macrophage system and regulatory T lymphocytes (T reg) (CD4+CD25+). Moreover the generation of T reg cells has been proven to be stimulated by macrophage-mediated chronic inflammatory status related to cancer progression. Therefore, it becomes to be clinically important to identify possible inexpensive biomarkers able to investigate and to define the immunoinflammatory status of cancer patients with the respect to more expensive analyses, such as the measurement of lymphocytes subset and cytokines blood concentration. Recent clinical studies have shown the common available inexpensive routinely laboratory analyses, such as lymphocytes-to-monocyte ratio (LMR) may reflect the immunoinflammatory status of cancer patients, since lymphocyte and monocyte count are respectively related to the anticancer immunity and to his macrophage mediated suppression. On this basis, a study was planned to establish which correlation may exist between LMR and lymphocyte subsets, namely T reg cells, in metastatic cancer patients. The study included 30 metastatic cancer patients, who were affected by the most common solid neoplasm. LMR and TH-TO-T reg ratio were considered to be normal when they were greater than 2.1 and greater than 10. Abnormally low values of LMR and TH-TO-T reg ratio were observed in 14/30 (47%) and in 16/30 (53%) patients, respectively. Patients with abnormally low values of TH-TO-T reg ratio showed significantly mean values of LMR than those with normal values. Moreover, a significantly positive correlation was observed between TH-TO-T reg ratio and LMR values. On the contrary, LMR was negatively correlated to T reg cell percentage. The results of this preliminary study would suggest that LMR may represent the best surrogate inexpensive biomarker with the respect to other most complex and expensive immune analyses to monitor the status of the immunoinflammatory biological response of cancer patients.