The current indoor thermal comfort standards and guidelines for hospital wards in the tropics may be insufficient for maintaining thermal comfort for occupants and ensuring energy efficiency in hospitals. Therefore, field survey assessments of thermal comfort were conducted in three Malaysian hospitals with air conditioning capabilities for patient rooms. This study evaluated existing thermal conditions and thermal comfort preferences of patients and their visitors. A total of 389 responses were collected in hot and humid conditions. Indoor thermal measurements were collected in each hospital and compared to the local guidelines. The lower temperature results compared to the Malaysian standard MS1525 (2014) and the Industry Code of Practice on Indoor Air Quality (2010) by the Department of Occupational Safety and Health (DOSH) in Malaysia indicated that specific thermal comfort guidelines were required for hospital wards in Malaysia. The mean comfort operative temperatures were estimated to be 25.3 degrees C for patients and 25.5 degrees C for visitors. The relationships between the indoor comfort temperature and running mean outdoor temperature (27.0 - 31.0 degrees C) in the three hospitals were also determined. These adaptive relationships can serve as a guide for building service engineers and researchers seeking to reduce energy use in hospitals. (C) 2018 Elsevier B.V. All rights reserved.