1. The molecular specificities of single mitral cells and their locations in the rabbit olfactory bulb were studied using extracellular recordings of single-unit spike discharges and oscillatory local field potentials. A panel of carboxylic acid molecules including a homologous series of fatty acids was used as odor stimuli. 2. Mitral cells showing excitatory responses to fatty acid molecules of different hydrocarbon chain length were localized near each other in a region in the dorsomedial part of the olfactory bulb. 3. Individual mitral cells in the dorsomedial region tended to respond to subsets of fatty acid odor molecules having similar hydrocarbon chain length or structure. Mitral cells responding to subsets of fatty acids of different chain length were distributed with partially shifted overlaps in this region. 4. The results show that stereochemical features of odor molecules are encoded by individual bulbar neurons.