This paper examines the numeral systems and the change in these systems in the Papuan language Mian (Trans New Guinea, Ok family) due to the influence of Tok Pisin. Mian has a binary numeral system consisting of a word for 'one' and a word for 'two'. As in other Trans New Guinea languages, there is also a body-part tally system in which certain points on the arms, the upper body, and the head and face are associated with numbers. The highest number in the Mian body-part system is 27. With the advent of western cash economy and currency Tok Pisin numerals and the decimal system have taken hold in the community and spread quickly. While the old binary system is still in use for both counting and modification of a noun in a noun phrase, the body-part tally system is defunct. This is in contrast to some other Trans New Guinea languages, for example Kalam and Oksapmin, in which the body-part system is still employed by older speakers. There is no evidence that the terms of the Mian body-part system have ever been used as numerals in the noun phrase. I suggest that the Mian system had a particularly hard time in surviving because it was restricted to the counting of temporal units even at the time when the linguistic work on Mian began.