TCC(graduação) - Universidade Federal de Santa Catarina. Centro de Ciências da Saúde. Farmácia.Laboratory turnaround time (TAT) has been used as an indicator of efficiency. Prolonged TAT causes delay on treatment, increases patient waiting time on emergency department and the risk for patient safety. Short TAT is important in poisoning cases. To decrease the time of the clinical decision, report of critical values is also important. To evaluate the efficiency of a public toxicology laboratory a user satisfaction survey was applied and TAT data collected. This laboratory serves the demands of a Brazilian Center for Information and Toxicological Assistance. The observed TAT met the laboratory's own deadline but not the user’s expectations and the one predicted by the UK guideline. Almost half of the users reported not being informed of the critical values. While everyone considered that communication is important, half of the users reported that it is not necessary. Although all users reported good satisfaction on laboratory results, opportunities for efficiency improvement were observed, such as reducing the test deadline, improving the test menu, and the communication of critical values.