In this analysis of cases and clauses in Vietnamese, an attempt is made to make use of tagmemics and a case grammar model called lexicase. Such an eclectic combination of the two theories is not new either in the field of general linguistics or in Vietnamese. This paper recognizes the hierarchical levels in syntax and the grammatical unit or tagmeme as composed of a slot and a filler class; it recognizes the case relations between various nouns and the predicative verb in the clause; and it also recognizes the centrality of the verb. Lexicase introduces both overt case realizations and covert case relations into the grammar as syntactic features assigned to nouns by verbs. The data presented here include: 12 covert case relations in Vietnamese; 11 overt case realizations; a two-dimensional matrix yielding 25 possible combinations of covert case relations and overt case realizations (25 tagmemic slots); 14 verb groupings classed according to their hospitality to case-marked tagmemic slots; five clause types classed according to their identificational-contrastive features such as the nuclear tagmemic slots; 13 clause classes; and a bi-dimensional matrix of the clause types and the clause classes giving 64 possibilities or clause units, of which only 51 are grammatical in Vietnamese. The intention is to present the data rather than to defend the linguistic models used. (Author)