A single crystal of the orthorhombic UGe₂ has been studied by magnetic (up to 5 T) and magnetotransport (up to 8 T) measurements. It was found that at low fields there exists a domain structure which is reconstructed to a monodomain one in fields higher than 0.1 T. The electrical resistivity has appeared to be highly anisotropic with \rho _b \gg \rho _c > \rho _a. For all three crystallographic directions the Fermi liquid equation is followed below about 8 K. Also the transverse magnetoresistivity (TMR) is anisotropic. At low temperatures the TMR for all three principal directions of the unit cell is positive and the values at 4.2 K and 8 T are in the following proportions 1:4:2 for TMR measured along the a-, b- and c-axes, respectively. At temperatures above about 15 (b-axis) and 25 K (a- and c-axes) the TMR becomes negative with a distinct minimum at T_C for the latter two directions. However, the most spectacular behaviour is observed when j||b and B||a. The TMR goes through very broad negative minimum achieving as high value as -40% at T=27 K, thus close to so-called characteristic temperature T^* (= 30 K), that is established from the maximum in the temperature derivative of the resistivity. So far the effect in TMR can be considered as the most distinct manifestation of the existence of magnetic fluctuations in UGe₂ taking place at temperatures at around 1/2T_C, without traces of a similar manifestation at T_C. The observed giant effect in magnetoresistivity can support the idea of the proximity of the system to a transition into the coupled CDW/SDW type ordering which probably takes place when applying pressure.

PACS numbers: 72.15.Gd, 75.60.--d, 75.30.Cr , 71.45.Le