The resistivity and Hall effect in CeNiSn are measured at temperatures down to 35 mK and in magnetic fields up to 20 T with the current applied along the b axis. The resistivity at zero field exhibits a quadratic temperature dependence below ∼0.16 K with a huge coefficient of the T2 term (54 μΩ cm/K2). The resistivity as a function of field shows an anomalous maximum and dip, the positions of which vary with field directions. Shubnikov-de Haas (SdH) oscillations with a frequency F of ∼100 T are observed for a wide range of field directions in the ac and bc planes, and the quasiparticle mass is determined to be ∼(10-20) me. The carrier density is estimated to be ∼10-3 electron/Ce. In a narrow range of field directions in the ac plane, where the magnetoresistance-dip anomaly manifests itself clearer than in other field directions, a higher-frequency (F=300-400 T) SdH osciliation is found at high fields above the anomaly. This observation is discussed in terms of possible field-induced changes in the electronic structure.