The extended tight-binding method is applied towards the investigations of the electronic structure of bulk Cu and a (001) Cu film. Detailed band structure total and orbital densities of states are presented for bulk Cu and compared with previously reported calculations and with photoemission spectra. Within the same calculational framework, the energy bands and the planar densities of states are obtained for a five-layer Cu(001) film. A marked variation of the local density of states is observed in the surface region. Their calculation clearly points to a d-band narrowing at the surface. Several surface resonances in the d-band of the thin film are identified. The authors have examined the sensitivity of their results to the choice of the exchange parameter alpha . By comparing the Fourier coefficients of the initial and resultant charge density the authors conclude that the results for alpha =1 are nearly self-consistent. The effect of varying the film thickness on the energy bands is also considered.