Directionality preferences in interpreting is a controversial topic for the academic and professional community, which questions which direction requires less effort and produces higher quality interpreting. In the case of oral language interpreters, it is suggested that the least difficult, accurate and preferred direction is towards the mother tongue. However, in signed languages, studies show the opposite preference, even though the professionals consider themselves to be less proficient and competent in sign language. With this non-experimental study with an exploratory-descriptive scope, we intend to find out the directionality preferences of Spanish sign language interpreters (ILSE) and the factors that condition them. A self-administered questionnaire was used in which 101 ILSE participated. The results suggest that professionals prefer and perceive a higher quality of interpretation into sign language, despite having acquired it as a second language and declaring themselves less competent. Among the factors that condition them, training, experience, and perceived difficulties in direct interpreting stand out. However, after this first approximation, we consider that it would be necessary to analyze the real difficulties of each interpreting direction and their impact on performance.