A large body of literature supports the notion that the language used in informed consent forms is not comprehensible to most research participants. Creating comprehensible informed consent forms for international research presents a further challenge because they are generally written first in English and then translated into the local language. The Kenya Medical Research National Ethical Review Committee determines readability of English consent forms before translation; however, it is neither their policy nor practice to determine whether the forms, once translated (...) into Kiswahili, are of comparable readability to the English forms. Thus, the aim of this study is to measure and compare the text difficulty in 10 pairs of English informed consent forms and their translated Kiswahili forms. The results show that a readable English-language consent form does not necessarily result in a readable form once translated into Kiswahili. (shrink)