The epidemiology of female sexual dysfunctions is still not well known. The Female Sexual Function Index (FSFI) is a short questionnaire specially designed to assess female sexual response. This study aimed to evaluate the cross-cultural equivalence of the Portuguese version of the FSFI. The cross-cultural adaptation involved five steps: translation, back-translation, formal equivalence assessment, review by specialists in sexuality, and pre-testing. After identification of semantic problems, agreements, and disagreements, a brief version was proposed, selecting and incorporating items from one of the two Portuguese versions. Some changes were made after pre-testing the questionnaire, most of which to make the Portuguese version more readily comprehensible and acceptable for the target population, using ordinary words as options or to complement the scientific language. Comparing more than one version of the instrument in the process of cross-cultural equivalence allowed detecting problems and difficulties in adapting the language, which would not have been observed otherwise.