The aim of this work was to examine the intraspecific diversity, sensitivity to antibiotics and antimicrobial activity of isolates of Pseudomonas spp. (n=40) isolated from a karst cave. All isolates were genotyped using the rep-PCR method. The highest intraspecific diversity was observed in the species P. chlororaphis, where the similarity varies from 50,5 to 100,0 %. Resistance to antibiotics was determined by the disk diffusion method for six classes of antibiotics and was proven in 30 tested strains. The largest number of strains (75 %) is resistant to monobactams, and one isolate (P. chlororaphis SL2-18) was resistant to three classes of antibiotics and belongs to multidrug resistant strains. Taking into account all degrees of activity, from weak to complete, strains of Pseudomonas spp. showed more pronounced antimicrobial activity against Gram-negative bacteria (89,0 %) compared to Gram-positive ones (84,0 %). In general, strains of Pseudomonas spp. proved to be the most effective in suppressing the growth of phytopathogenic bacteria E. amylovora and A. tumefaciens and the least effective in controlling the growth of human pathogens S. aureus and S. enterica. The strain of Pseudomonas spp. W2-4 proved to be the most effective, completely suppressed the growth of three pathogens (L. innocua, E. amylovora and A. tumefaciens), and strongly inhibited the growth of the bacteria P. syringae and E. coli. Antifungal activity was determined in 13 strains (32,5 %) of which six (15,0 %) inhibited the growth of the fungus B. cinerea very strongly with a range of radial growth reduction of 84,1±1,7 % from 93,9±5,2 %. The strongest antifungal activity was found in Pseudomonas spp. S1-8 strain, which reduced the radial growth of B. cinerea by 93,9±5,2 %, and in the P. chlororaphis SL2-11 strain, which reduced the radial fungal growth by 90,2±0,0 %.