Fumonisins, a family of mycotoxins, are mainly toxic and carcinogenic. The present study was carried out to evaluate fumonisin B1 (FB1) effects on the production of inflammatory cytokines by gastric and colon cell lines. The study was performed on two cell lines under in vitro condition, including gastric epithelial cell line (AGS) and human colon adenocarcinoma cell line (SW742). Lipopolysaccharide (LPS) was used for inflammatory cytokine induction. The culture medium was supplemented with 4.5-72 mg/l of FB1 for 72 h before cell induction. The supernatants were harvested 24 h after the induction and measured for cytokines by using enzyme-linked immunosorbent assay.FB1 induced a dose-dependent increase in the production of tumor necrosis factor-α and interleukin-1β in both AGS and SW742 cell lines. This increase was statistically significant with concentration of FB1 between 9 and 72 mg/l (P < 0.05). FB1 also induced a dose-dependent decrease in interleukin-8 production. This decrease was seen in both cell lines and showed a statistical significance with FB1 concentration (P < 0.05).The results show that FB1 increases inflammatory cytokines production by various gastric and intestinal cells. This effect in the long run can possibly be the basis for the occurrence or development of inflammation and subsequent atrophy in the above-mentioned tissues.