Most translations are needed for technical documents in specific domains and often the domain knowledge available to the translator is crucial for the efficiency and quality of the translation task. Our project1 aims at the investigation of a MAT-paradigm where the human user is supported by linguistic as well as by subject information ([vHa90], [vHAn92]). The basic hypotheses of the approach are: - domain knowledge is not encoded in the lexicon entries, i.e. we clearly distinguish between the language layer and the conceptual layer; - the representation of domain knowledge is language independent and replaces most of the semantic entries in a traditional semantic lexicon of MT/MAT-systems; - the user accesses domain information by highlighting a sequence in the source text and specifying the type of query; - factual explanations to the user should be simple and transparent although the underlying formalisms for knowledge representation and processing might be very complex; - as a language for knowledge representation, conceptual graphs (CGs) of Sowa [Sow84] were chosen. In providing connections between the terms (lexical entries) and the knowledge base our approach will be compared to terminological knowledge bases (TKBs) which are hybrid systems between concept-oriented term banks and knowledge bases. This paper presents: - a contrastive view to knowledge based techniques in MAT, - mechanisms for mapping the "ordinary" linguistic lexicon and the terminological lexicon of two languages onto one knowledge base, - methods to access the domain knowledge in a flexible way without allowing completely free linguistic dialogues, - techniques to present the result of queries to the translator in restricted natural language, and - use of domain knowledge to solve specific translation difficulties.