Higher Twist Contributions to Deep-Inelastic Structure Functions

We report on a recent extraction of the higher twist contributions to the deep inelastic structure functions $F_2^{ep,ed}(x,Q^2)$ in the large $x$ region. It is shown that the size of the extracted higher twist contributions is strongly correlated with the higher order corrections applied to the leading twist part. A gradual lowering of the higher twist contributions going from NLO to N$^4$LO is observed, where in the latter case only the leading large $x$ terms were considered.