Synthetic cannabinoids, which were synthesized to improve the therapeutic effects of cannabis, have become a major issue when they are abused. They have different chemical structures from tetrahydrocannabinol (THC) but similar effects on endocannabinoid receptors. "Spice'' named products have more serious side effects than cannabis and can even cause death. These mixtures are prepared by spraying chemicals onto small pieces of herbs and are being dishonestly sold as "natural'' and "legal'' products over the internet. Their popularity is continuously increasing. Studies on detecting synthetic cannabinoids in biological samples as well as pharmacology and toxicology studies of these chemicals are very limited. A fast, specific and robust method for the detection and quantification of JWH-073, JWH-073 N-butanoic acid, and JWH-073 N-(4-hydroxybutyl) in blood and urine has been developed that uses solid-phase extraction (SPE) followed by UPLC-MS/MS analysis. This method has been validated in terms of its linearity (0.1-50 ng/mL), selectivity, intra-assay and inter-assay accuracy and precision (CV < 10%), recovery (75-95%), limits of detection (LODs) (0.08-0.13 ng/mL), and limits of quantification (LOQs) (0.11-0.17 ng/mL). Matrix effects, stability, and process efficiency parameters of this method have also been assessed. This method was applied to 2596 authentic samples received by the Department of Toxicology (Istanbul) in the Presidency of Council of Forensic Medicine (Turkey) between September 1, 2012, and February 28, 2015. (C) 2015 Elsevier Ireland Ltd. All rights reserved.