The goal of each company today is to improve business and increase profit through the reorganization and simplification of its processes, decrease of costs and resources utilization etc. Improving the business is usually implemented through different techniques and methodologies that have been developed. One of the ways to improve service processes, and health system processes also, is the implementation of the lean concept. This study shows benefits from using Lean tools value stream mapping (VSM) and simulations to simplify the laboratory work process. Using the VSM and simulation in department of clinical biochemistry authors showed significant improvement of the clinical processes such as eliminating non-value added times (NVAT) by minimum 30 working days/year, increasing number of laboratories analyses by approximately 80.000 analyses/year, eliminating unnecessary movement of 39,000-52,000 meters/year for samples and 78,000-104,000 meters/year for stuff and decreasing patient waiting times from average 70 to 20 min/patient.