MicroRNAs (miRNAs) are involved in most cellular processes and are deregulated in several diseases. Antisense miRNA oligonucleotides (AMOs) therefore present novel therapeutic opportunities. Currently, in vivo delivery of AMOs often relies on high doses of nucleic acids, with nonspecific uptake by most tissues. Critically, AMOs accumulate in phagocytic cells where they can interfere with immune functions, such as the activation of Toll-Like Receptors (TLRs). In this chapter, we describe a method to assess the possible off-target effects of AMOs on TLR7, 8, and 9 sensing.