Nonfluorescent pseudomonads have been studied by estimating their numbers in different soils and hortical substrates as well as some physiological properties and antagonistic relationships between them and fluorescent pseudomonads and actinomycetes. Nonfluorescent pseudomonads, depending on the studied soil or substrate, constituted 7-10% of the total number of bacteria from genus Pseudomonas, and the dominant among them were pectinolytic psychrotrophs. Antagonism of nonfluorescent pseudomonads was less frequent and less intense than that of fluorescent pseudomonads as counter-partners. On the other hand, in the system of interrelationships with actinomycetes, the antagonism of nonfluorescent pseudomonads was relatively more frequent, though its intensity was lower.