The study analyses the performances of a hospital cleaning service managed in outsourcing with respect to the balance between available resources and expected quality standards. Data were referred to a high specialization hospital and were collected through a multiple approach (interviews, cost analysis, performance simulations and field investigations). A difference (48%) emerged between expected and observed standards. In order to quantify the estimated gap, two models were examined with respect to personnel costs (euro 7.09/hr for NHS personnel and euro 4.5/hr for private personnel). Additional resources needed to achieve required standards resulted respectively 182% and 115% of the invested budget. This result stresses the importance to define the minimum standard to be guaranteed for safe and clean environment in health care organizations and the break-even point between quality and costs, leaving the single institutions the decision about additional quality level and resources needed for it.