Abstract: Objective: Scavenging free radical and antibacterial activities in vitro of two metallothionein isomeric forms from yeast and metallothioneins from animal were compared.Methods: Measuring the free radical clearance rate of metallothioneins and compared with that in control group ( VC) by UV.The antibacterial activities of metallothioneins against staphylococcus aureus, E. coli and listeria were discussed. Results: The hydroxyl and DPPH radical scavenging capacity of metallothioneins were stronger than VC, but the superoxide anion radical scavenging capacity of metallothioneins were less than VC.And metallothioneins also had the inhibiting effect on staphylococcus aureus and bacteria listeria.The scavenging free radical were Zn- MT > MT- Ⅰ > MT- Ⅱ.Conclusions: Metallothioneins had powerful capacity on scavenging free radical scavenging and certainly antibacterial action on some pathogens, the effects were different because of metal sulfur protein sources, purity and configuration.