Formaldehyde and acetaldehyde concentrations have been measured in indoor environments of various public spaces (railway station, airport, shopping center, libraries, underground parking garage, etc.) of Strasbourg area (east of France). In addition, formaldehyde, acetaldehyde propionaldehyde and hexanal concentrations have been measured in 22 private homes in the same area. In most of the sampling sites, indoor and outdoor formaldehyde and acetaldehyde concentrations were measured simultaneously. Gaseous aldehydes levels were quantified by a conventional DNHP-derivatization method followed by liquid chromatography coupled to UV detection. Outdoor formaldehyde and acetaldehyde concentrations were both in the range 1–10μgm−3, the highest values being measured at the airport and railway station. Indoor concentrations were strongly dependant upon the sampling sites. In homes, the average concentrations were 37μgm−3 (living rooms) and 46μgm−3 (bedrooms) for formaldehyde, 15μgm−3 (living rooms) and 18μgm−3 (bedrooms) for acetaldehyde, 1.2μgm−3 (living rooms) and 1.6μgm−3 (bedrooms) for propionaldehyde, 9μgm−3 (living rooms) and 10μgm−3 (bedrooms) for hexanal. However, concentrations as high as 123, 80 and 47μgm−3 have been found for formaldehyde, acetaldehyde and hexanal respectively. In public spaces, the highest formaldehyde concentration (62μgm−3) was found in a library and the highest concentration of acetaldehyde (26μgm−3) in the hall of a shopping center. Additional measurements of formaldehyde and acetaldehyde were made inside a car both at rest or in a fluid or heavy traffic as well as in a room where cigarettes were smoked. Our data have been discussed and compared with those of previous studies.