The aim of this study was to present the synthesis, characterization and anticancer activities of two novel benzimidazole-based NHC salts (1a-b) and their silver(I) complexes (2a-b) with methylbenzyl and isopropylbenzyl chains. All compounds were prepared using Schlenk techniques in an inert atmosphere. The carbene complexes were prepared with the interaction of carbene precursors and Ag2O. All new compounds were characterized by elemental analysis, LC-MS, FT-IR, H-1 NMR, and C-13 NMR spectroscopic techniques. The anticancer activities of the salts and complexes were determined by cell proliferation analysis using (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay on human prostate cancer cells (DU-145) and human breast cancer cells (MCF-7, MDA-MB-231). L-929, mouse adipose tissue fibroblasts were used as model normal cells. The cells were plated at a cell density of 1 x 10(5) cells in 96-well plates and treated with different concentrations (1-20 mu M) of salts and complexes during 24, 48 and 72 h. The MTT assay results indicated that the salts (1a-b) have lower anticancer activity on cancer cells than their silver(I) complexes (2a-b). It was also observed that benzimidazole salts (1a-b) and their Ag-NHC complexes (2a-b) displayed lower anticancer activities on L-929 normal cells than on cancer cells. These results highlight that the anticancer activities of N-heterocyclic carbene-silver complexes vary according to the structure of the silver complex and cell line type. (C) 2019 Elsevier B.V. All rights reserved.