In the textile industry, many attempts have been made to resist fiber against rapid growth of microorganisms such as microbes. Hence, the development special fibers by using simple methods have been special demands. In this thesis, antimicrobial properties of acrylic fibers with application of metal salts were studied. To this concept, some metal salts, namely copper sulfate, zinc sulfate, zinc chloride and aluminum sulfate with six direct dyes, i.e. C.I.Direct Blue 168, C.I.Direct Yellow 12, C.I.Direct Red 23, C.I.Direct Red 31, C.I.Direct Black 38 and C.I.Direct Green 6 have used. Antibacterial properties of acrylic fibers during pre-mordanting, dyeing, after-mordanting by using mentioned direct dyes and metal salts against Staphylococcus aurous , a gram-positive bacterium and Escherichia coli and Pseudomonas aeruginosa , two gram-negative bacterial according to AATCC test method 100-1993 was evaluated. Different concentration of mordant, time and temperature was optimized. As following, we investigated light and washing fastness, k/s value, spectrum absorbance and FT-IR spectra of samples. Evaluation of antibacterial properties of treated samples by using different direct dyes and metal salts showed in compare with another samples in pre-mordanting and after-mordanting process has the best antimicrobial properties. Also, pre-mordanted and after-mordanted fabrics with copper sulfate and dyed with C.I.Direct Blue 168 and C.I.Direct Green 6 indicated most and lowest antibacterial activity, respectively. The results show that light and washing fastness of treated samples with copper sulfate have a good light and moderate washing fastness. Also, treated fabric with 0/5% owf copper sulfate has highest. FT-IR analysis indicated that peak at 1665 cm -1 which can be attributed to amid carbonyl group in fiber, is disappeared.