Sri Lankan inpatients receive a discharge summary in English known as a diagnosis card. The authors investigated whether supplementing the diagnosis summary with native language improved patients’ knowledge of illness and medication. Participants were 130 newly diagnosed patients with noncommunicable chronic diseases (92 men, 70.8%; 38 women, 29.2%; M age = 55.4 years, SD age = 12.8 years) who were randomized to a control group receiving an English discharge summary and intervention group receiving a supplementary native language discharge summary. A questionnaire assessed knowledge of illness and prescribed medications at discharge and at 2 weeks. The groups were comparable for knowledge of diagnosis and prescribed medications at discharge. At 2 weeks, the intervention group had significantly higher scores than did the control group for knowledge on diagnosis, M = 81.41, SD = 34.63, versus M = 27.95, SD = 41.26, respectively, p < .001; and on medications, M = 54.48, SD = 33.91, versus M = 12.55, SD = 20.44, respectively, p < .001. The increase in scores was explained by the dichotomous variable, whether supplementary discharge summary was given or not (p < .001). A higher proportion in the intervention group read the discharge summary to gain knowledge of diagnosis (81.5%) and medication (80%) than in the control group (4.6% and 6.2%, respectively; p < .001). A total of 121 participants (92.1%) preferred a discharge summary in native language. This simple model may be useful to improve patient knowledge relating to illness in countries that predominantly use another language for medical communications, rather than a native language.