Abstract: The research indicated a gap in existing knowledge regarding the impact of teamwork quality on New Product Development (NPD) cycle time through the mediation of internal market orientation in the telecommunication industry in Saudi Arabia. The aim of this study was to obtain the mediating effect of market orientation on the relationships the independent variables of top management, inter-departmental dynamics, organizational system and the dependent variable of business performance. Random sampling was used to select respondents for a survey from among members of NPD teams in Saudi telecommunications firms with total respondents 149 teams and response rate of 88.67%. Findings indicated that internal market orientation was found to affect positively NPD cycle time. Internal market orientation fully mediated the relationship between balance of member contribution, mutual support and NPD cycle time. Internal market orientation partially mediated communication, coordination, efforts and cohesion and NPD cycle time.