Fire retardant and heat resistant yarns, fabrics, felts and other fibrous blends which incorporate high amounts of oxidized polyacrylonitrile fibers. Such yarns, fabrics, felts and other fibrous blends have a superior LOI, TPP and continuous operating temperature compared to conventional fire retardant fabrics. The yarns, fabrics, felts and other fibrous blends are also more soft and supple, and are therefore more comfortable to wear, compared to conventional fire retardant fabrics. The yarns, fabrics, felts and other fibrous blends incorporate up to 99.9% oxidized polyacrylonitrile fibers, together with at least one additional fiber, such as p-aramid, in order to provide increased tensile strength and abrasion resistance of the inventive yarns, fabrics, felts and other fibrous blends. The yarns may be woven, knitted or otherwise assembled into a desired fabric.