Abstract In the present paper we present our attempts to study whether carbon nano tubes (CNT) are safe materials to be administeredin the living system. For this purpose effect of CNTs on the lymphocyte of peripheral blood sample of healthy persons as well asallergic patients were studied. Allergic patients were considered because CNT can be allergic to certain individuals. Cell growth,viability, apoptosis and metabolic activity were evaluated in proliferating human peripheral blood lymphocytes. Theconcentrations of CNTs tested were 1, 2.5, 7.5 and 10 μg/ml; and treatment duration of 72 h, in accordance with the biologicaltarget investigated. A statistically significant decrease in cell growth was found in cells treated with 7.5 and 10 μg/ml CNT inhealthy individuals but not in the allergic patients. [avf_view name="Article Addons" view-id="66d98451c48e3"]