This research is on adverbial clauses in Tonga. Adverbial clauses in many world languages have been generally analysed to have conjunctions that introduce them. Most of the adverbial clauses in Tonga, however, do contain conjunctions that cannot stand alone but are expressed with elements attached to verbal constituents. Some adverbial clauses do not even contain a syntactic conjunction. Since the elements in verbal forms do not introduce the adverbial clauses, these elements have been viewed as elements signalling adverbial clauses. The study used a descriptive research design. Data was purposively selected. Only adverbial clauses with such phenomenon were selected for analysis.