Introduction (Purpose) - The main purpose for this study is to study internal communication challenges from a managerial and employee perspective in two interrelated IT departments. Furthermore this study aims to give suggestions for how organizations can improve their internal communication within and between departments. Design/methodology/approach - The research setting took place in a Swedish telecom company where data was collected during 10 weeks. An abductive scientific approach was used with an extension of mixed methods with a triangulation design. Interviews and survey were made to both managers and employees as primary data, whereas different kinds of observations, informal interviews and meetings, intranet and employee satisfaction scores were used as secondary data. Findings - Findings show several internal communication challenges, such as different definitions of what internal communication stands for, too many media channels put strains on the internal communication within and between IT departments which results in unsynchronization. The organizational structure itself creates internal communication challenges as a result of not sharing common goals and strategies, but also responsibility issues which leads to misunderstanding and conflicts. To improve internal communication challenges between the departments, some of the following examples were found; the need of overcoming unsynchronization, shared goals and strategies, common messages from head managers in order to reduce problems related to co-operation between the departments and desideration of an interactive communication tool. Practical implications – Deal with misunderstandings to prevent internal communication challenges. Interrelated departments should strive for alignment through common goals and strategies. More interactive communication tools such as social networks could promote more effective internal communication. Originality/value – Rich data collection by using mixed methods resulted in empirical findings that address internal communication challenges between two IT departments with an organizational structure that reminds of a line-and-staff organization from a managerial and employee perspective. / <p>This thesis has been professionally proofread</p>