Ambient levels of formaldehyde and acetaldehyde have been measured at four locations in the Atlanta, Georgia, area during July and August 1992. Location-averaged concentrations were 2.7 - 3.0 ppb for formaldehyde and 2.6 - 3.2 ppb for acetaldehyde (2 hr - samples). The highest concentrations measured were 8.3 ppb for formaldehyde and 8.4 ppb for acetaldehyde. On the average, ambient aldehyde concentrations measured at two elevations (6 m and 30 m) at a near-downtown location were similar; those recorded at a predominantly upwind site were slightly lower, and those recorded at a predominantly downwind site were slightly higher. The formaldehyde/acetaldehyde concentration ratio (ppb/ppb) ranged from 0.2 to 3.3 and averaged 1.04 ± 0.46 (217 samples). A brief discussion of the data is presented and includes method performance evaluation, diurnal variations, examination of the acetaldehyde/formaldehyde concentration ratio, and comparison with literature data for other urban areas.