Abstract: A method, an apparatus, and a computer program for measuring a quality of the machine translation. An original segment, for example one sentence in English, is translated to a target language, for example Spanish. The translated sequence is translated and then back-translated with several machine translation engines back to the original language, for example English. The resulting translations, back-translations are compared, possibly to each other, and to the original sequence. This gives measurement value of the quality of the back translations. At least one measured value from above steps of the process can be used in order to output information about the quality of the machine translation.