Abstract. Poly(ADP-ribose) polymerase-1 (PARP-1) which mediates poly-ADP-ribosylation, has been extensively investigated in carcinoma compared to arginine ADP-ribosyltransferase 1 (ART1), which mediates mono-ADP-ribosylation. Previous studies have demonstrated that these enzymes promote proliferation and tumor development in colon carcinoma. However, whether there is any association between PARP-1 and ATR1 in colon carcinoma, remains unelucidated. In this study, using immunohistochemical analysis, we detected a higher expression of PARP-1 and ART1 in 63 samples from patients with colon carcinoma compared to 10 samples of normal colonic mucosa; our results revealed a positive correlation between the expression of PARP-1 and ART1 in the 63 human colon carcinoma tissue samples. To determine the correlation between PARP-1 and ART1, inhibitors of PARP-1 and ART1 and lentivirus vector-mediated ART1 short-hairpin RNA (shRNA) were used to culture CT26 murine colon adenocarcinoma cells separately. Using double-label immunofluorescence assay, we detected the expression of PARP-1 in the CT26 cells, which was decreased following treatment with 5-aminoisoquinolinone (5-AIQ, a PARP-1 inhibitor) or meta-iodobenzylguanidine (MIBG, an ART1 inhibitor). However, the expression of ART1 only decreased when the CT26 cells were treated with MIBG. Furthermore, our results demonstrated that silencing ART1 inhibited PARP-1 expression by decreasing the expression of nuclear factor-κB (NF-κB), inhibiting ras homolog A (RhoA). Hence, our data demonstrate the positive correlation between ART1 and PARP-1; the inhibition of ART1 activity downregulates PARP-1 expression by decreasing the activity of NF-κB in CT26 colon carcinoma cells.