Background: A number of cytokines are produced when interleukin-29 (IL-29) is introduced to monocytes. High creation of IL-6, IL-8, and IL-10 was seen after stimulating human monocytes with IL-29. The cytokine Interlukin-19 belongs to the interleukin-10 family. When interleukin-29 was added to monocytes, IL-19 production was increased. In response to IL-29, monocytes exhibited rapid morphological changes.  Objective: To study and focus on role of Interleukin-29 in autoimmune diseases.  Methods: We scoured medical papers and databases including PubMed, Google Scholar, and Science Direct for information on IL-29 and autoimmune illnesses. Only the most recent or comprehensive study conducted between April 2002 and December 2020 was included in the analysis. The authors also assessed the usefulness of references drawn from similar books. Documents written in languages other than English have been neglected because of a lack of funding to translate them. Unpublished articles, oral talks, conference abstracts, and dissertations were all generally agreed upon not to constitute valid scientific investigation. Conclusion: As a newly found type III interferon, interleukin-29 (IL-29) is an exciting discovery. It mediates signal transmission and results in the generation of inflammatory components via interactions with its receptor complex that initiate further signal transduction. Recent studies have linked dysregulated IL-29 expression to a wide variety of inflammatory autoimmune diseases, involving osteoarthritis, systemic sclerosis, rheumatoid arthritis, psoriasis, systemic lupus erythematosus as well as Sjögren's syndrome. Furthermore, functional investigation suggested that IL-29 may contribute to the onset of autoimmune inflammatory disorders.