Seven microorganisms capable of killing Pomacea canaliculata were isolated from soil samples obtained from various agricultural areas of Thailand. The identification of these microorganisms was performed using microscopic examination and biochemical tests. Five strains were identified as Pseudomonas aeruginosa and were designated P. aeruginosa 19.1, 21.2.1, B1.1, P1 and P2. The other two strains were identified as Pseudomonas fluorescens and were designated P. fluorescens 13.1 and Ct1. Pathogenicity studies of these microorganisms to P. canaliculata (Lamarck) were performed and characterized by LC50 levels. The LC50 levels of non-autoclave-treated and autoclave-treated cell suspensions to P. canaliculata were found to be 3.56 × 104–1.35 × 106 c.f.u./ml and 3.09 × 104 to 1.23 × 106 c.f.u./ml, respectively.