alpha-Conotoxins possess a conserved four-cysteine framework and disulfide linkages (C1-3, C2-4) that fold toward the globular conformation with absolute fidelity. Despite the presence of a similar conserved set of cysteine framework, chi/lambda-conotoxins adopt an alternate disulfide-pairing (C1-4, C2-3) and its consequent ribbon conformation, exhibiting distinct biological activities from alpha-conotoxins. chi/lambda-Conotoxin CMrVIA (VCCGYKLCHOC-COOH) isolated from the venom of Conus marmoreus natively exists in the ribbon conformation and induces seizures in mice at a potency that is of three orders higher than the non-native globular form. We have chemically synthesized two isoforms of CMrVIA conotoxin in the ribbon and globular conformation and determined their structures by H-1 NMR spectroscopy. The ribbon (PDB ID 2B5P) and globular conformations (PBD ID 2B5Q) were calculated to have paired-wise backbone RMSDs of 0.48 +/-0.1 and 0.58 +/- 0.1 angstrom respectively. Unlike the native globular alpha-conotoxins, the globular canonical form of CMrVIA chi/lambda-conotoxin exhibited heterogeneity in its solution structure as noted by the presence of minor conformers and poorer RMSD of structure calculation. Paired-wise backbone comparison between the native ribbon and the non-native globular form of CMrVIA conotoxin revealed an RMSD of 4.73 angstrom, emphasizing their distinct conformational differences. These structural data are essential for the understanding of the structure-function activity of chi/lambda-conotoxins, as well as unraveling the folding propensities of these short peptide toxins.