Saliva or "oral fluid" has been presented as an alternative matrix to establish drug exposure. The noninvasive collection of an oral fluid sample, which is relatively easy to perform and can be achieved under close supervision, is one of the most important benefits when testing for driving under the influence of drugs. Moreover, the detection of Delta9-tetrahydrocannabinol (THC) in oral fluid is a better indication of recent use than a positive urine test, so there is a higher probability that the subject is experiencing pharmacological effects at the time of sampling. Twenty-five subjects (5 free and 20 addicts from a heroin detoxification center) were included in a study to evaluate the potential application of a new device, the Cozart DDSV (drug detection system visual), to detect cannabis in oral fluid. The time cannabis was last smoked was recorded by the medical staff after interview with each subject. Samples were collected with the Cozart DDS Oral Swab and diluted with the Cozart DDS buffer as proposed by the manufacturer. The Cozart DDSV test was conducted on site at the time of collection, and the remainder of the sample retained for confirmation analysis by gas chromatography with mass spectrometry (GC/MS) after methylation of THC (limit of quantitation 0.5 ng/mL). All 25 samples were analyzed by GC/MS. On-site results were obtained within 10 minutes. The 5 drug-free subjects were negative for cannabis, irrespective of the method. From the 20 subjects declaring that they had smoked cannabis between 30 minutes and 24 hours previously, the DDSV device identified 8 positive subjects (with THC concentrations in the buffer in the range 15-219 ng/mL), whereas 18 subjects tested positive using GC/MS. THC concentrations in the Cozart buffer using GC/MS analysis ranged from 0.7 to 219 ng/mL. These concentrations represent about one third the authentic THC concentrations in oral fluid due to the dilution by the liquid of the device. Given the results, the DDSV device was considered as an acceptable tool to detect cannabis abuse in oral fluid within a period of 2-3 hours after smoking.