Patients' satisfaction with cancer care has not been studied in detail in the South-Asian region in spite of rising cancer incidence. To validate the 'Sinhala' translation of the European Organization for Research and Treatment of Cancer (EORTC) in-patient satisfaction with care questionnaire (IN-PATSAT32) in Sri Lanka. We administered the translated version of the IN-PATSAT32 on 343 newly diagnosed adult in-patients with cancers of head and neck, breast, oesophagus, cervix uteri and lung, recruited from seven tertiary care oncology treatment centres in the District of Colombo. Patients with previous cancer diagnoses, too frail/mentally unfit, with evidence of brain metastases and unable/unwilling to give informed consent were excluded. Psychometric testing assessed the hypothesized scale structure, scale reliability, construct validity and acceptability of the IN-PATSAT32. A high response rate (100%) and low missing data (0.05%) confirmed the acceptability of the IN-PATSAT32. The hypothesized scale structure was confirmed with 100% item-convergent and 98.6% item-discriminant validity, and a scaling success rate, defined as items correlating significantly higher (more than 1.96 standard errors) with its own scale (corrected for overlap) than with another scale, of 97.9%. The Cronbach's alpha coefficient for internal consistency exceeded 0.70 in all scales. Construct validity was confirmed with inter-scale correlations, which were all statistically significant (P<0.01) and were of moderate-to-high magnitude, evidence that they were measuring distinct dimensions of patient satisfaction. The translated version of the IN-PATSAT32 has proved to be a reliable and valid measure of satisfaction with cancer care in patients with heterogeneous cancer diagnoses in Sri Lanka.