A minimally invasive testing methodology was developed to monitor the in-service performance of soft body armor. In the spirit of the single fiber test standard, ASTM C 1557-03, the fiber diameter was measured at five equally spaced locations along a 6-cm gauge length specimen. In addition, the single fiber test specimen was modified by placing reflecting tape just outside the specimen gauge length to allow the use of a laser extensometer for directly measuring fiber displacement and hence, strain. This modified testing methodology was found to be reproducible and provide data that was normally distributed based on descriptive statistics when variations in the fiber diameters along the length of the specimen were considered. The abnormality in the data, identified using Pierce's outlier criterion, may be associated with processing variations during the fiber manufacture and/or the woven fabrics and not associated with the testing methodology. Furthermore, the failure strain was found to be drastically reduced when the minimum fiber diameter along the length of the test specimen was less than 11 mu m. This suggests that a methodology that accurately profiles fiber diameter changes along the gauge length of the fiber may be useful in analyzing single fiber test results. (c) 2008 Wiley Periodicals, Inc.