Abstract: This invention relates to the filling or dispensing of radiopharmaceuticals in sample vials. Radiopharmaceuticals must be dispensed in a cleanroom environment according to cGMP regulations. Single-use filling cassette-type dispensing systems can be used for filling or dispensing of radiopharmaceuticals in sample vials. A single-use filling cassette is the core of such a dispenser system. A flexible bag container comprising a flexible bag and a filling cassette was found. The filling cassette is assembled within the flexible bag under aseptic conditions. The assembled filling cassette defined a closed system since each opening is connected to a sample vials or sterile filter avoiding contamination from outside.