The ATP-binding cassette sub-family G member 2 (ABCG2) is implicated as a member of multidrug resistant proteins in tumors, mediating efflux of a wide spectrum of anticancer drugs. Pro-inflammatory cytokines, which are present within the micro-environment of tumors and inflammation, are able to modulate the expressions and activities of different drug transporters. This study was aimed to evaluate the short-term (72-h treatment) effects of interleukin-1β (IL-1β), tumor necrosis factor-α (TNF-α), and interleukin-6 (IL-6) on the expression and function of ABCG2 in cervix carcinoma and gastric cancer cells. Effects of pro-inflammatory cytokines on mRNA, protein expression, and function of ABCG2 were studied using real time RT-PCR and flow cytometry methods, respectively. HeLa cells treated with IL-1β, IL-6, or TNF-α showed decrements in ABCG2 mRNA levels without any changes in protein expression and function of ABCG2. IL-6 and TNF-α had no effects on mRNA, protein expression, and function of ABCG2 in EPG85-257 cells. Although IL-1β did not alter ABCG2 at mRNA or protein levels in EPG85-257 cells, it augmented function of ABCG2 in these cells. Mitoxantrone accumulation was also amplified in IL-1β-, IL-6- or TNF-α-treated HeLa cells and in IL-1β-treated EPG85-257 cells. In conclusion, pro-inflammatory cytokines were able to modulate the expression of ABCG2 at transcriptional and post-transcriptional levels in human cervix and gastric cancer cells.