The clinical COPS was supplemented with items to cover two new dimensions: Pre-admission visit and Operation Room. It was sent to a sample of day care patients of five general Dutch hospitals to investigate dimensionality, acceptability, reliability, construct and external validity. Construct validity was established by correlating the dimensions of the COPS-D with patients’ overall satisfaction.The COPS-D was returned by 3802 patients (response 46%). Factor analysis confirmed its’ structure: Pre-intake visit, Admission, Operation room, Nursing care, Medical care, Information, Autonomy and Discharge and aftercare (extraction communality 0.63-0.90). The internal consistency of the eight dimensions was good (α？=？0.82-0.90); the item internal consistency corrected for overlap was satisfactory (>0.40); all inter-item correlations were higher than 0.45 but not too high (<0.90). The construct validity of all dimensions was good (r from 0.52-0.62, p？<？0.01). The Information dimension had the strongest correlation with overall day care satisfaction.The COPS-D is a reliable and valid instrument for measuring satisfaction with day care. It complements the model of measuring patient satisfaction with clinical and outpatient care given in hospitals. It also fulfils the conditions made while developing the clinical and outpatient COPS: a short, core instrument to screen patient satisfaction.