Homocysteine (Hcy) is a non essential-sulfur containing aminoacid derived from methionine. The data available so far shows that Hcy is an independent risk factor in atherosclerosis. This work aimed at studying the levels of serum Hcy in healthy active, passive and non-smoker subjects. This study revealed that smoking, whether active or passive, resulted in increased tHcy levels which may be attributable to decrease the folate and vitamin B12.Also, elevated tHcy levels were related to age, extent and duration of cigarette smoking and high blood pressure which all contribute to cardiovascular risk profile.