This paper will examine concerns over Mahyna influence in the bhikkhunī movement in contemporary Sri Lanka. Although the number of Sri Lankan women receiving bhikkhunī ordination has increased steadily since the late 1980s, the concern over Mahāyāna influence remains an important factor in the legitimization of the nuns' bhikkhunī status in Sri Lanka. In order to understand the historical and political contexts behind those concerns, this paper will first will give a brief introduction to the history of Sri Lankan Buddhist nuns' order, from its first introduction to the island to its recent revival. Secondly, this paper will discuss a few elements frequently cited by Sri Lankan Buddhists as the basis to refute Mahyna elements. The third part is the main theme of this paper: it will examine the postcolonial anxiety behind the concerns over Mahyna influence. Many argue that since the late 19(superscript th) century, there has developed a strong association between Sinhala nationalism and Theravāda Buddhism. I will argue that it is out of this association that Mahāyāna elements in the transmission of bhikkhunī ordination pose a challenge to many Sri Lankan Buddhists.