BACKGROUND Data on quality indicators (QIs) should be collected over time in order to identify and continuously monitor clinical laboratory performance and to improve patient safety by identifying and implementing effective interventions. The aim of the present study was to ascertain whether the utilization of a set of quality indicators over a 3-year period resulted in an improvement in the efficiency and effectiveness of an individual laboratory. METHODS Over a 3-year time interval (2009-2011), a series of 38 QIs covering all stages of the total testing process (21 in the pre-analytic, nine in the analytic and eight in the post-analytic phase) was monitored. RESULTS On the basis of their patterns, QIs have been grouped into the following categories: [1] seven QIs of the pre-analytical phase and three of the intra-analytical phase with a significant trend and a significant linearity demonstrating an improvement over time; [2] 10 QIs of the pre-analytical and two of the intra-analytical phase with a significant trend and a non-significant linearity demonstrating that changes were not constant; [3] two QIs of the pre-analytical and one of the intra-analytical phase with a non-significant trend and significant linearity showing neither improvement nor worsening; and [4] two QIs of the pre-analytical and three of the intra-analytical phase with a non-significant trend and non-significant linearity. CONCLUSIONS Data on a set of QIs collected over a 3-year time-frame demonstrate that processes and indicators under the control of the clinical laboratory had improved much more than processes requiring close co-operation between the laboratory and care teams.