It is critical that packages containing sterile medical devices maintain a sterile barrier until the device is used. In 1995, a study conducted by the Health Industry Manufacturers Association (HIMA) compared a whole-package microbial challenge test to physical integrity testing ; published results indicated the superiority of physical tests. This paper discusses the problems with the classic approach to whole-package microbial challenge, outlines a new whole-package microbial challenge test, and details the work done to begin to illustrate its effectiveness. The project aim is the creation of a new methodology for microbial challenge testing of medical device packages that reduces the chance of false positives that were commonly observed with the previous technique. The proposed method involves aseptically filling sterile, sealed packages with growth media, challenging them with microbes, incubating the package, and then conducting colony counts to determine package contamination. Results suggest that the proposed technique does not have the false positives that were associated with historical microbial challenge testing. False positives are a serious problem, as they indicate that a package has not maintained its sterile barrier when, indeed, it has. This can lead manufacturers to false assumptions about production and the package, potentially resulting in increased costs for healthcare providers and patients. Research presented here represents the first step in creating a standardized methodology for whole-package microbial challenge testing. Currently, such a test does not exist. While there are numerous physical integrity tests that a manufacturer of medical devices can employ to verify the integrity of packages before release to the market, a need exists for a standardized whole-package microbial challenge test that overcomes the difficulties associated with those of the past.