France is the country with the highest prevalence of cannabis use in Europe, despite the fact that cannabis has not been legalized. This prevalence is still increasing along with THC content in cannabis products. In the meantime, unintentional cannabis poisoning by ingestion in toddlers is constantly rising. The aim of this study was to document children's cannabis poisoning biologically and clinically. Plasma and urine samples were extracted by solid phase extraction and analyzed by liquid chromatography coupled to tandem mass spectrometry. Children under 4 years old admitted in pediatric emergency departments for cannabis intoxication between February 1st 2019 and January 31st 2020 were included in this study. Twenty-six children were included (14 female and 12 male), the mean age was 17 months (10-41 months). THC, 11-OH-THC and THC-COOH plasma concentrations ranged from 2.9 to 93 ng/mL, 2.6-65 ng/mL and 29-914 ng/mL, respectively. The most frequent symptoms were drowsiness and hypotonia. Six critical cases were observed: 5 coma and 1 respiratory depression. All children having THC plasma concentrations over 60 ng/mL were in coma. Cannabis poisoning in toddlers become more frequent, 9 cases/year were reported in Marseille in 2007 and 26 cases/year in this study. There is a rising in severe clinical cases, particularly coma. These observations could be explained by an increase in THC content in cannabis products, and a trivialization of cannabis consumption. The unintentional ingestion of cannabis by children is a serious public health concern, and cannabis legalization could worsen this problem.