Cleaning validation is an integral part of current good manufacturing practices in any Biopharmaceutical industry. Drug products usually get contaminate with residue of other drug products or cleaning agents manufactured in the same equipments, if the cleaning procedure is not proper. We studied the cleaning validation of GCSF Injection on three consecutive batches in multi product manufacturing facility. Various acceptance limits for product carryover was calculated based on 0.1 % of therapeutic dose, 10 ppm and 1/1000 Therapeutic daily dose of the drug. The stringent limit of maximum allowable carryover (MACO) of GCSF in other products was found to be 18 µg. The 0.5 M NaOH solution was used as a cleaning agent to clean the equipments and accessories used for bulk manufacturing of GCSF. Rinse and swab samples were collected from the cleaned equipments and accessories and tested for product carryover by sandwitch ELISA. The product carryover of GCSF in subsequent product was determined to be less than 0.1 µg and the level of cleaning agent was less than 10 ppm, thus indicating establishment of effective cleaning procedure for GCSF manufacturing.