This article explores the application of data-driven machine translation (MT) to sign languages (SLs). The provision of an SL MT system can facilitate communication between Deaf and hearing people by translating information into the native and preferred language of the individual. In this paper we address data-driven SL MT predominantly for Irish SL (ISL) but also for German SL (DGS/Deutsche Gebärdensprache). We take two different purpose-built corpora to feed our MaTrEx MT system and in a set of experiments translating both to and from the SLs, we investigate the effects of SL data on statistical MT (SMT). Exploiting the bidirectionality of the MaTrEx system, we demonstrate how additional modules, such as recognition and SL animation, can potentially build a full SL MT model for spoken and SL communication in addition to promising evaluation scores. A secondary focus of the article is on the two main issues affecting SL MT, those of transcription and evaluation. We offer a discussion on both these common problems before concluding. © 2013 Springer Science+Business Media Dordrecht.