Synthetic cannabinoids are a significant public health and safety problem that complicates drug tests with their ever-changing structures in our country and worldwide. The fact that most synthetic cannabinoids cannot be detected in biological samples by routine drug of abuse screening tests also causes an increase in the use of these substances in return. In this study, 500 urine samples of randomly selected probationers, analyzed with an enzymatic immunoassay test at Ege University Institute of Drug Addiction, Toxicology and Pharmaceutical Sciences (BATI) and tested negative, were then selected for retrospective analysis. Synthetic cannabinoids and their metabolites were quantitatively scanned in the collected urine samples via the liquid-liquid extraction method with the LC-MS/MS. Of the 500 studied urine samples, 108 (21.6%) were positive for 20 synthetic cannabinoids and their metabolites. The two most detected synthetic cannabinoids were 5F-NPB-22 (58%) and (S)-AB-FUBINACA (36%), and their mean concentrations were 72.94 +/- 47.51 ng/mL and 5.84 +/- 14.7 ng/mL, respectively. These results were also compared with national statistics from the general population. It resulted that immunoassay screening tests used in this study were insufficient, and urine samples should be studied in clinical and forensic cases with a validated chromatographic method.