Lanthanide (Ln) extractions from organic acids to n-dodecane by N,N,N', N'-tetraoctyl-diglycolamide (TODGA) were conducted. Four organic acids (lactic acid, malonic acid, tartaric acid, and citric acid) were employed. Although these acids stabilize lanthanides in the aqueous phase, a distribution ratio (D) greater 1 was obtained for heavy Ln. Ln patterns (D(Ln) against atomic number of Ln) show maximum values of Ho and Er. In order to obtain high D values, the addition of HNO3 in aqueous phase was found to be effective.