Parasites have been shown to up- and downregulate host apoptosis, most likely facilitating their ability to successfully establish an infection in the host. It has been demonstrated that pathogens modulate well-established pathways, leading to cell death, including induction of the Fas–FasL system to promote apoptosis. In contrast, it has also been shown that in other instances a decrease in host cell apoptosis results after the upregulation of genes in the Bcl-2 family. The present study examined the ability of Trypanosoma cruzi to modulate expression of host cell genes of the TNFR1 apoptotic pathway. Using microarray technology, gene expression was compared between uninfected BALB/c fibroblasts and T. cruzi–infected BALB/c fibroblasts. After comparing expression patterns between uninfected and T. cruzi–infected BALB/c fibroblasts, it was concluded that genetic expression of genes in the TNFR1 apoptotic pathway is downregulated in T. cruzi–infected cells, indicating that in BALB/c fibroblasts the parasite decreases the expression of genes, leading to host cell apoptosis.