Four to five holes covering 2,500 metres are planned to target a significant copper-molybdenum-gold anomaly identified by recent soil sampling.
The drilling will confirm the historic drilling results and to test for extensions to the mineralisation at depth, the junior said.
Tethyan believes mineralisation is likely to extend to significant depth and that the concentration of mineralisation may increase the further down you go.
It is obliged to complete at least 2,000m of drilling before 28 December.
Peter Mullens, chief executive, said: "We are excited by our first drill program at Rudnitza.
Initial surface geochemistry and mapping returned highly encouraging results indicating that the size of the mineralised porphyry system is much larger than previously recognised.”
Assay results will be available in late-January 2017, he added.