HVDC transmission line designs are in many respects similar to those of high voltage AC transmission lines. The key differences are that most HVDC lines are connected to bipolar converters and therefore, use only two pole conductors; one for the positive pole and the other for the negative pole. Some lines, however, include a neutral conductor in case the neutral current is not permitted to be conducted through the ground (earth) between the connected converter stations. Where neutral current is allowed to flow through the ground the cost of overhead (OH) line towers is reduced because only two conductors instead of three are used in the right-of-way (ROW). The DC field effects are more benign than those around AC OH lines. That is, an HVDC OH line can be less costly to build than a comparable HV AC OH line, which compensates for the cost of the HVDC converter stations connected to the line. This chapter present information about economics, tower designs, conductor configurations, and includes an overview of HVDC field effects and reliability considerations to guide those considering construction of an HVDC OH line.