Murine hybridoma cells can produce monoclonal antibody (MAb) and the production of these antibodies in culture and peritoneum can be affected by different factors, including stimulants, inhibitors and supplements. Among these factors, the impact of micronutrients on the production of MAbs by mouse hybridoma cells has not fully been explored. In this study the murine hybridoma cells, M3C5, were cultured and treated with different concentrations of ATRA and DHA, alone, in combinations, and at different time of exposure. Then, changes in the production of MAb in culture medium were evaluated using ELISA. The hybridoma cells after single and combined treatment with ATRA, DHA and vehicles were IP injected to Balb/c mice and the changes in production of MAb in ascites were determined by ELISA. The results showed that single and combined treatment of ATRA and DHA elevated the production of MAb by hybridoma cells in both in vivo and in vitro. The production of MAb following in vitro single treatment with 1 μM of ATRA and 10 μM of DHA for 2 days was significantly increased. The in vitro effects of ATRA on increase of MAb production was obtained more than DHA. The MAb productions in combined treatment with 0.5 μΜ of ATRA plus 5 μΜ of DHA were significantly increased in in vivo and in vitro. However, the effect of DHA was obtained more significant in in vivo conditions. The results of this study showed for the first time that in vitro and in vivo treatments of ATRA and DHA could increase the production of MAb in mouse M3C5 hybridoma cells.