MedSLT is a grammar-based medical speech translation system intended for use in doctor-patient diagnosis dialogues, which provides coverage of several different subdomains and multiple language pairs. Vocabulary ranges from about 350 to 1000 surface words, depending on the language and subdomain. We will demo three different versions of the system: an any-to-any multilingual version involving the languages Japanese, English, French and Arabic, a bidirectional English <-> Spanish version, and a mobile version running on a hand-held PDA. We will also demo the Regulus development environment, focussing on features which support rapid prototyping of grammar-based speech translation systems.