APOBEC3G (apolipoprotein B mRNA-editing enzyme catalytic polypeptide-like 3G) is known to have a role in intrinsic cellular immunity against human immunodeficiency virus type1 (HIV-1). The antiretroviral activity of APOBEC3G (APO3G) is associated with the hypermutation of viral DNA through cytidine deamination. APO3G contains two cytidine deaminase domains that are characterised by highly conserved zinc-coordinating motif. It is known that only the C-terminal domain of APO3G (c-APO3G) has the catalytic activity. To shed light on the molecular mechanism of action by which APO3G inactivates HIV-1, we have undertaken the structural and binding studies by NMR. Here, we show the achievement of backbone assignments of c-APO3G and the identification of the secondary structure deduced from chemical shift index (CSI) and NOE data.