Polyhexamethylene guanidine hydrochloride and polyhexamethylene biguanidine hydrochloride were polycondensated in the melt of monomers. The intrinsic viscosity and (M) over bar(n) were determined by the viscosity of dilute polymer solution and VPO, respectively. Polyhexamethylene guanidine stearate and polyhexamethylene biguanidine stearate were synthesized using the precipitation reaction for the first time. NMR, FTIR, XPS and element analysis were used to analyze the chemical structure and element composition. The structure of the resultant polymers is coincident with the theoretic structure. The minimal inhibition concentration (MIC) was measured to characterize the antimicrobial activity of the products. The MIC is not larger than 200 mu g ml(-1). The polymeric guanidine and biguanidine are effective in controlling bacteria and fungi. The TG test shows that the resultant polymers are stable to heat.