Worldwide scientific data show that there is an increasing level of resistance to carbapenems among Enterobacteriaceae rods. We examined the genetic similarity and antimicrobial susceptibility of four KPC-2-positive Klebsiella pneumoniae (with gene bla KPC ) which were isolated (for the first time Poland). Among KPC-2-producing isolates, three isolates (USK1/1, USK2/1, USK4/1) with a similarity of >98% belonged to cluster A, and one (DSK1/1) was dissimilar (<95%) to all the other isolates.