CONTEXT: Assessment of cleaning cost of hospitals is important for hospital administrators, infection control experts and housekeeping managers. Such data are lacking in the medical literature. AIMS: The aim of this study was to determine the cleaning cost of a tertiary care not-for-profit private cancer hospital. SETTINGS: This study was conducted in Tata Medical Center, Kolkata, India, which has 183 inpatient beds. DESIGN: This was a retrospective observational study. MATERIALS AND METHODS: Cleaning cost assessment was done from financial records over one financial year (April 2015–March 2016). The methodology involved taking into account the cost of various types of wastes (general, biomedical and microbiological), human resource cost (housekeeping staff salary), laundry cost, costs of cleaning equipment, cost of consumables (personal protective equipment, soap solutions, disinfectants, cleaning mops etc.) and the cost of water consumption. STATISTICAL ANALYSIS: No special statistical tests were used. RESULTS: The cost of keeping the hospital clean was INR Rs. 49,206,015 ($745,546 USD/€668,854). This comprised 4% of the total operational expenditure of the hospital. The maximum proportion of cost for cleaning hospitals was due to housekeeping staff salaries (66%), followed by cost of laundry (17%) and cost of cleaning consumables (13%). The trend analysis of the multidrug-resistant organism (MDRO)-related bacteraemia rate during the study period (calendar year of 2015 and 2016) showed a slight reduction of Methicillin- resistant Staphylococcus aureus, Vancomycin- resistant Enterococci and extended-spectrum beta-lactamase and AmpC beta-lactamase bacteraemia rates. CONCLUSION: Keeping hospital clean is resource intensive. This is an essential strategy to keep MDRO infection rates under control.