Because of inconsistencies in literature data, the crystal structure of ZrTe 3 was redetermined from single-crystal data and the electronic band structure was calculated using density functional theory in the local density approximation (LDA) and the linear muffin tin orbital method (LMTO). ZrTe 3 crystallizes in the monoclinic space group P2 1 /m with a ؍ 589.8(1) pm, b ؍ 392.69(3) pm, c ؍ 1010.3(1) pm, and ؍ 97.81(1)°°(Z ؍ 2) in the ZrSe 3 structure type ( data collection, R w ؍ 1.88%). In the layer structure of ZrTe 3 almost linear homonuclear Te chains in [100] direction with alternating distances of 279.4(1) and 310.5(1) pm are observed. In addition to these, there are several other Te-Te distances below the sum of the radii of Te 2؊ ions (370-380 pm). From the band structure calculations we found these homonuclear contacts to be responsible for the unexpected metallic conductivity of ZrTe 3 . The calculation of the Fermi surface revealed three branches. The one caused by the intersection of E F with bands of predominantly Te chain character shows an extended region of approximately parallel Fermi surface. The nesting vector, which lies in the range ql + + (0.95 ؎0.05)al *؉ (0.35؎0.15)cl *, is in fair agreement with data from an electron diffraction study of ZrTe 3 , which has shown the presence of a charge density wave at a temperature of 63 K with the vector ql + +0.93al *؉0.33cl *.