Abstract : This is the first description of the structure of the number system of Dzongkha, the national language of Bhutan. Two parallel systems are described, a decimal system, used in formal occasions, and a vigesimal system used for everyday life. We note the presence, in the vigesimal system, of interesting features such as fractional count, over-counting, and the obligatory mention of unit-counters (as distinct from classifiers). Grouping by pairs, and measure systems, especially an extended system of length measurements based on the human body are also note-worthy. the data was collected in 1977. It seems that the use of the vigesimal system is now (2010) endangered.