The continuously growing NK-92 cell line is highly cytotoxic against a broad spectrum of tumor targets and has completed phase I clinical trials in humans. To further improve the anticancer activity towards ErbB2 expressing cancer cells NK-92 cells were generated under GMP-compliant conditions with an ErbB2-specific humanized CAR construct by lentiviral gene transfer. In order to establish a platform for a broad NK-92 cell based clinical therapy we established a GMP-compliant Master cell stock (MSC) comprising 200 ampules of 2,5x10e7 CAR expressing NK-92 cells. For qualification and release testing of the MCS, the identity and potency of the NK-92 cells, stability of CAR expression, and the absence of adventitious agents were monitored by numerous tests in cooperation with Bioreliance. The GMP-compliant MCS of a humanized CAR expressing ErbB2-specific NK-92 cells meets all required specification (identity, stability, potency, sterility) and can serve as a platform for future clinical trials.