We describe a bidirectional version of the grammar-based MedSLT medical speech system. The system supports simple medical examination dialogues about throat pain between an English-speaking physician and a Spanish-speaking patient. The physician's side of the dialogue is assumed to consist mostly ofWH-questions, and the patient's of elliptical answers. The paper focusses on the grammar-based speech processing architecture, the ellipsis resolution mechanism, and the online help system.