There is growing awareness concerning the variety of VOCs as well as their level in the indoor air. Measurements of VOCs were carried out in both the indoor and the outdoor air of six office buildings in Greece together with the measurements of other physical and chemical parameters. The experimental results showed that the toxic VOC (TVOC) concentrations in 65% of the rooms were higher than the recommended level of 200 pg-m-3 and that the concentrations of TVOCs in the outdoor air were lower than the concentrations in the indoor air in all the buildings examined. More than 60 compounds were identified from the TVOCs in each building among which the aromatic and aliphatic compounds were the most abundant. Although a number of other compounds were found, including terpenes, ketones, alcohols, aldehydes,esters and halogenated compounds, most of them did not exceed the level of 20 pg-m~3 in most of the rooms.