Nicotiana tabacum hairy roots that express the antibody 14D9 were established. The 14D9 antibody yield obtained after 20 days of culture was 5.95 μg 14D9ml^-1. The addition of the reticulum endoplasmic retention sequence KDEL demonstrated a positive effect over the intracellular 14D9 amounts with a yield increase up to 20.82 µg ml^-1. DMSO increased the antibody amount in the biomass from 20.00 to 64.03 µg ml^-1 while PVP (at 1.5 gl^-1) and gelatine (at 5.0 gl^-1) increased total 14D9 amounts in the culture medium to 25 µg and 14 µg respectively.