Modern undyed natural fiber textile fabrics were experimentally biodegraded for use in archaeological textile conservation research. Specimens were exposed to soil burial in sandy loam, soil burial in peat, and prolonged soaking in unchanged distilled water for periods of 0.5-32 weeks. The degraded fabrics were evaluated by microscopic examination, chemical analysis, and physical methods of testing. Results of macro- and micromorphological analysis are reported. Fabric cross-sections were analyzed using light microscopy, and fabric, yarn and fiber surfaces were examined by scanning electron microscopy. Soil burial was more aggressive than prolonged soaking, and sandy loam more aggressive than peat except for the wool. Cellulose-based fabrics were less resistant to biodegradation than protein-based fabrics, linen was less resistant than cotton, and wool was less resistant than silk. Based upon visual assessment, the experimentally-degraded fabrics are similar to both water-degraded archaeological textiles and burial-induced degraded modern textiles reported by other studies.