Objectives: Objectives of this study were to develop a method for determination of phenol with gas chromatography-mass spectrometry, determine optimal parameters of the instrument and to quantify the phenol in three different biological samples of urine by using the selected method. Settings: LABORATORY OF TOXICOLOGY, DEPARTMENT OF PATHOLOGY, MEDICINE AND CYTOLOGY, University Hospital of Split. Materials and methods: Four mixes of standard solutions were prepared by gradually diluting phenol with chloroform. Three different groups of instrumental parameters were selected (method 1, 2 and 3) to determine which method gives the best signal on the chromatogram. A voluntary defined volume of MIX 2 was injected in three urine samples. The samples were prepared for the analysis by using solid phase extraction and analyzed with GC-MS method. Results: By analysing three equal concentrations of standard solution using all three methods, it was noticed that method 3 gives the best signal on the detector. Parameters of analysis for method 3 were: injection volume:1 μl , injector temperature:250 °C, carrier gas flow (helium):1,54 ml/min, program time:10 minutes (60 °C for 1 minute and 10 °C per minute til 170 °C). Two out of three urine samples were successfully detected and quantified with phenol. Sample 1 had the phenol concentration of 593,74 ng/ml and sample 2 1080 ng/ml. Conclusion: It is possible to detect and quantify the phenol from the biological samples of urine by using selected method 3. SPE is a good technique of sample preparation, but additional analysis are neccessary to establish the quantity of interferences that drop behind and can affect the analysis.It is also neccessary to carry out additional analysis on real biological samples to be able to confirm these techniques of sample preparation and analysis.