Onconase(®) FL-G zymogen is a 120 residue protein produced by circular permutation of the native Onconase(®) sequence. In this construction, the wild type N- and C-termini are linked by a 16 residue segment and new N- and C-termini are generated at wild type positions R73 and S72. This novel segment linking the native N- and C-termini is designed to obstruct Onconase's(®) active site and encloses a cleavage site for the HIV-1 protease. As a first step towards the resolution of its 3D structure and the study of its structure-function relationships, we report here the nearly complete NMR (1)H, (13)C and (15)N resonance chemical shift assignments at pH 5.2 and 35°C (BMRB deposit no 17973). The results presented here clearly show that the structure of the wild type Onconase(®) is conserved in the FL-G zymogen.