Due to the biological synthesis of biotechnologically produced pharmaceuticals the product quality and safety of the drug is influenced by various factors. The correct nucleotide sequence and stability of the host cell/vector system provide the corresponding amino acid sequence of the protein. The posttranslational processing of the protein requires a well characterized production cell line. Suitable equipment for fermentation allowing a sterile production of the producing monoculture and consistent conditions are the basic requirements for the validation of the fermentation process. A constant specific productivity is one of the major criteria for the reproducibility of the production. For the validation of recovery and purification it is necessary to examine yield after each process step, product quality before and after each single process step and purification factors for removal of contaminating proteins, nucleic acids and potential viruses. In addition to the validation of the entire production process, reproducibility of quality of the formulated product has to be determined by a number of protein analytical, immunological and biochemical test methods concerning the identity, purity, safety and potency of the drug.