Due to the magnitude and complexity of many of these projects, contractors have resorted to subcontracting to share responsibilities and mitigate project risks. The Zambian government has also invigorated the practice of subcontracting in the construction industry as it plays an imperative role in increasing economy viability and development of local contractors. Ministerial Statement on July 25, 2012 directed RDA to ensure minimum of 20 percent sub-contracting on all major road contracts to Zambian-Owned Companies. Instead of improving project success, subcontracting can act as a catalyst for poor project outcomes. Though there are many reasons that contribute to problems from subcontracting, a strained relationship between main contractors and subcontractors can be seen as a notorious contributor to poor project outcome. The study aimed at investigating the relationship between main contractors and subcontractors in Zambia, establish factors leading to interface problems and those factor that can help improve this relationship. Questionnaire survey was adopted in order to collect data and investigate the relationship. A total of 80 questionnaires were distributed. The questionnaires were distributed by hand and via email. Out of the targeted 80 respondents 56 responded, giving a response rate of 70 percent. The study established that the relationship between main contractors and subcontractors in Zambia needed to improve, as it was not in an effective state. Interface problems were caused by payment issues, poor communication, unexpected price escalations and poor construction work. In order to address interface problems, the study found that there was need for better communication between the parties, timely payments and subcontractors’ access to labour and machinery