Abstract: A sterility testing apparatus for membrane filtration and direct inoculation sterility testing is disclosed. The apparatus has a test receptacle and preferably a sample receptacle. A sample flowpath directs the test sample to the test receptacle and a further flowpath directs wash and/or culture media to the test receptacle. The further flowpath has a microorganism filter arrangement upstream of the test receptacle to filter out microorganism contaminating the wash and/or culture media before it is introduced into the test receptacle. The possibility of “false positive” test results which indicate the presence of microorganisms when none, in fact, are present in the sample being screened, is therefore advantageously reduced compared to known sterility testing systems.