Datura inoxia belongs to the family of Solanaceae. This is a very common plant in New Caledonia that contains two main toxic alkaloids, l-atropine and l-scopolamine. In this study, we report the case of a 20-year-old male admitted to an Emergency Unit after consumption of 6 dried flowers in hot water for hallucinations, mydriasis, and agitation associated with tachycardia and increase of systolic blood pressure to 180. Full recovery was observed after one week. Three weeks later, a lock of about 80 hairs (200 mg) was collected from the subject in vertex posterior with scissors to be tested for both atropine and scopolamine. After decontamination with dichloromethane, a strand of hair was segmented into three parts, cut into small segments (< 1 mm), incubated overnight in 1 mL pH 8.4 phosphate buffer in the presence of 2.5 ng atropine-d(3), the internal standard, then extracted with 5 mL dichloromethane/isopropanol/n-heptane (50:17:33). The residue was reconstituted in 100 microL of methanol, from which 10 microL was injected into an XTerra MS C18 column (100 x 2.1 mm, 3.5 microm) eluted with a gradient of acetonitrile and formate buffer delivered at a flow rate of 0.2 mL/min. A Quattro Micro triple-quadrupole mass spectrometer (MS) was used for analyses. Ionization was achieved using electrospray in the positive ionization mode. For each compound, detection was related to two daughter ions (atropine: m/z 290.2 to 124.0 and 92.9; atropine-d(3): m/z 293.1 to 127.0 and 92.9; scopolamine: m/z 304.1 to 138.0 and 156.0). Although atropine was never detected (limit of detection = 2 pg/mg), scopolamine was identified in the three segments, in the range 14 to 48 pg/mg. The absence of atropine in hair is consistent with its very low dosage in the flower of Datura inoxia. Hair segmentation indicated that the subject was previously exposed on several occasions to the plant. Liquid chromatography-tandem MS appears to be a necessity for testing tropane alkaloids of the Datura group, given the low concentrations to be measured.