Due to the concern of equating correct pronunciation with comprehension and the differences in health care systems, existing health literacy (HL) instruments may not be appropriate for or applicable to English-speaking countries other than the USA. The purpose of this study was to develop and validate the Health Literacy Test for Singapore (HLTS), which is an adapted version of the Short-Test of Functional Health Literacy in Adults. Three hundred and two patients were interviewed and administered the HLTS, the Newest Vital Sign (NVS), a demographic questionnaire, and a knowledge test of chronic diseases. The convergent validity of HLTS was determined by examining the association between HLTS and NVS HL levels, whereas predictive validity was tested by examining the difference in knowledge of chronic conditions between the two HLTS HL (i.e. adequate and inadequate HL) groups. Bivariate correlation of HLTS HL levels with age and education was assessed to test a priori hypotheses that patients with inadequate HL were older and less educated. The results showed that HLTS displayed good internal reliability (Cronbach's alpha = 0.87). The correlation between HLTS and NVS was moderate (γ = 0.55; P = 0.005) and individuals with inadequate HL were older (P = 0.002) and less educated (P = 0.007). In addition, patients with adequate HL had a higher mean score on the chronic disease knowledge test (P = 0.036). In conclusion, the HLTS is a valid and reliable measure for assessing Singaporeans ability to read and comprehend health-related materials written in English.