Abstract Contractors, consultants, and decision makers are challenged to estimate time and cost of new pipe installations using Horizontal Directional Drilling (HDD). This is because productivity prediction and cost estimation of HDD involves a large number of objective and subjective factors that need to be considered. Therefore, the main objective of the present research is to identify and study the factors that affect productivity of HDD operations. To achieve this objective a thorough literature review is carried out and data on potential factors impacting productivity are collected from HDD experts across North America and abroad. The presented research identifies 13 factors classified under four main categories: managerial, mechanical, environmental and pipe physical conditions. The impact of these factors on HDD productivity is assessed within three types of soils: clay, rock, and sand. Analytical hierarchy process (AHP) technique is used to quantify this impact and rank these factors according to their relative importance. Results show that pipe diameter, operator and crew skills, soil type, and steering problems have the highest impact on HDD productivity as evaluated by many experts in the field. However, pipe type, length and depth are the least impacting factors. This analysis is proved to be helpful for contractors, consultants and HDD professionals in predicting execution time and estimating cost of HDD projects during the pre-construction phase.