Volatile organic compounds (VOCs) have been determined to be human risk factor in urban environments, as well as primary contributors to the formation of photochemical oxidants. Concentrations of VOCs were measured at five monitoring sites located in the greater Cairo area, Egypt, as a part of the air pollution study.  On each sampling day, 22 abundant VOCs  were collected three times per day  (7-9 in the morning,  2-4 afternoon and 8-10 evening) during the period from March 2003 to March 2004,  to observe diurnal variations of volatile organic compounds on the air of Greater Cairo area and air quality information system in Egypt. Most of the VOCs species showed diurnal variations with higher concentrations during the morning and evening, and lower concentrations during the afternoon. However, in the afternoon , the concentrations of aromatic compounds, closely correlated with solvent usage such as toluene, ethyl benzene, m-/p- xylene, and o-xylene, were slightly higher than or comparable to those in the morning. This may be due to the increase of evaporative emissions derived from the rise in ambient temperature and additional sources such as the use of solvents in petrol, painting, printing and dry cleaning.