Multiplexed error-robust fluorescence in situ hybridization (MERFISH) is a massively multiplexed single RNA-molecule imaging technique capable of spatially resolved single-cell transcriptomic profiling of thousands of genes in millions of cells within intact tissue slices. Initially introduced for brain tissues, MERFISH has since been extended to other tissues, where rapid RNA degradation during the preparation process can pose challenges. This protocol outlines the application of MERFISH in one such challenging tissue, the mammalian gastrointestinal tract. We describe two complementary protocols leveraging either fresh frozen or fixed frozen approaches and describe methods for combining RNA imaging with immunofluorescence. While these protocols were designed and validated in gut tissues, we anticipate that they will be useful resources for the application to other challenging tissue types.