The authors report on colossal electroresistance (ER) in the ferromagnetic insulator manganite La0.9Sr0.1MnO3. The single crystal samples exhibit a transition into a low resistive state above a certain threshold current. Pulsed measurements demonstrate that this transition is not a consequence of heating. ER behaves similarly to magnetoresistance (MR) above the orbital order temperature T-OO. Below T-OO the MR is only 20% while ER enhances the conductivity by several orders of magnitude. Magnetic field and electric current have opposite effects on the conductivity, therefore, it seems that only the injected carriers are able to modify the ordering of e(g) Mn orbitals. (C) 2007 American Institute of Physics.