A series of low-density polyethylene (LDPE) antibacterial functional plastics were prepared by mechanical blending with commercial chitosan (CS), self-made water-soluble chitosan (W-CS), and microchitosan as antibacterial agents. The effects of the antibacterial agent content on the elongation at break of the obtained plastics were tested, and the bacteriostatic effects against Escherichia coli, Bacillus subtilis, and Proteus species were investigated. The results indicate that the elongation at break of LDPE with antibacterial agent decreased and had a slower decline when the mass ratio of CS to LDPE was greater than 0.5 : 100. The LDPE-based plastics showed different antibacterial activities against the three experimental strains, and plastics with W-CS exhibited the best antibacterial activity against B. subtilis. However, the antibacterial content had little effect on the antibacterial ratio. Moreover, 6-week soil burial tests indicated that the addition of CS caused a decrease in the resistance of LDPE to microbiological deterioration in a natural environment. (C) 2009 Wiley Periodicals, Inc. J Appl Polym Sci 113: 2018-2021, 2009