Abstract: The National Hospital of Sri Lanka (NHSL) is the largest teaching hospital in Sri Lanka and the country final referral center consisting of 3280 beds. As biochemical tests are widely used to diagnose diseases and monitor treatments, Biochemistry laboratory plays a significant role in providing health care. The Biochemistry laboratory of NHSL receives more than 1000 tests on average per day. An error that occurs at the laboratory may cause a complete change in diagnosis and the treatment process. Therefore, the quality of service provided by the laboratory should be optimized.