Abstarct: abstract One of the major geotechnical challenges that can significantly affect the performance and stability of structures, and may even lead to their failure, is the presence of problematic soils, which include dispersive, expansive, collapsible, and liquefiable soils. This study focuses on collapsible soils and evaluates the influence of adding animal fibers on the mechanical behavior of cement-stabilized samples. The experimental program involved assessing the effects of varying fiber contents on the unconfined compressive strength of collapsible soil stabilized with different cement percentages, as well as examining the impact of fibers on standard Proctor compaction test results. The results indicate that specimens containing 1% and 0.5% fibers showed an increase of approximately 1.92 to 2.10 times in unconfined compressive strength compared with the reference sample. Among cement-treated specimens, increasing the cement content to 12% led to a sixfold increase in compressive strength relative to the reference sample (0% cement and 0% fibers), while the failure strain decreased by 21.04%. For uncured specimens containing both fibers and cement, increasing the cement content from 1% to 12% in samples with 1% fibers resulted in nearly a fourfold increase in compressive strength and a 68.65% reduction in failure strain. Additionally, in specimens containing 12% cement and 0.5% fibers, extending the curing time from 0 to 28 days produced a sixfold increase in compressive strength and a 72.34% reduction in failure strain. Overall, increasing the curing time consistently enhanced compressive strength and reduced failure strain. These findings demonstrate that cemented fiber-reinforced specimens exhibit higher compressive strength and lower failure strain compared with fiber-only reinforced specimens, while standard compaction test results revealed that for a fixed cement content, increasing the fiber percentage decreases the maximum dry density and increases the optimum moisture content.