The findings show that LC/MS is a viable method for analyzing dye colors in polyester and acrylic fibers. Parameters were optimized for disperse and basic dye classes in order to allow for the separation and identification of dyes through mass spectral and ultraviolet-visual microspectrophotometry data. Single fibers were successfully extracted and analyzed by using these methods including the use of a novel acetonitrile extraction for disperse dyes from polyester fibers in lieu of pyridine. A master method developed separated and identified both disperse and basic dye standards. Continuing development of LC/MS analysis for all dye classes as well as the development of an extended spectral database will provide a greater ability to distinguish dye colors in forensic fiber analysis. The description of the experimental procedures covers the high performance liquid chromatography/ultraviolet-visible microspectrophotometry, the spectrophotometer used and associated procedures, dye standards, how the fabrics were dyed, dye extraction, basic dye and disperse dye chromatography optimization, disperse dye extraction system development and evaluation, and single-fiber analysis. 4 tables, 7 figures, and 14 references