Subgingival plaque samples were taken from upper and lower right canines, premolars, and first molars (distal, mid-buccal and lingual) in 10 periodontally healthy individuals after four days without oral hygiene. The samples were examined in the darkfield microscope. Counts and proportions of morphotypes were related to the location of the sampled sites. The influence of site location on the distribution of morphotypes was studied by multiple regression analysis. Inter-individual differences were significant for the proportions of cocci, nonmotile rods and fusiform organisms (p less than 0.001), the influence of site location was not. Significant differences (p less than 0.05) were found between total bacterial counts of samples taken from different sites: Distal-buccal samples contained more bacteria than did mid-buccal samples, mid-buccal ones contained more than lingual samples; samples from more posterior teeth contained more bacteria. The experiment was repeated after 5 weeks. The intertest agreement (kappa) for the presence of the different morphotypes ranged between 0.13 and 0.30. Coefficients of variation of the proportions of morphotypes determined in repeated samples were between 1.35 and 3.13.