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Objective: To determine cannabinoid-levels in blood and driving-related ability after single (S1) and repetitive (S2) vapor inhalation of cannabis low in Δ9-tetrahydrocannabinol (THC), but high in cannabidiol (CBD). Methods: In a prospective, randomized, cross-over study at the Institute of Forensic Medicine Basel, healthy adults (NS1=27, NS2=20) vapor-inhaled two low-THC/CBD-rich products (both Outcomes: i) THC- and CBD-levels in whole blood, ii) assessment of driving-related ability.Results: Among 74 participants included, 27 (mean age ± SD, 28.9 ± 12.5 years) completed S1, and 20 (25.2 ± 4.0) completed S2. THC dropped below 1.5 µg/L after 1.5 h, but was detected up to 5 h. Pairwise comparison of driving-related ability revealed no significant differences between low-THC/CBD-rich products (P1, P2) and placebo (P1 - P2: β = 0.319 [95% CI, -1.731 to 2.368], p = 0.950; P1 - placebo: β = 0.854 [95% CI, -1.329 to 3.037], p = 0.724; P2 - placebo: β = 0.535 [95% CI, -1.632 to 2.702], p = 0.879).Conclusions: Detection of THC after consumption of low-THC/CBD-rich cannabis might have legal consequences for drivers. Regarding overall driving-related ability, no significant differences were observed between interventional products.Trial Registration: German Clinical Trials Register: DRKS00018836.