Zopiclone is a hypnotic agent belonging to a class of non-benzodiazepine hypnosedative drugs, the cyclopyrrolones. Fatal poisonings are mainly represented by suicides, often in combination with other drugs. To our knowledge, no deaths have been reported in children. We present here a double infanticide with premeditation by zopiclone administration and drowning. Two young boys, 2- and 5-year-old respectively, were found dead in a bathtub full of water. Suspicions quickly turned to the mother who rapidly confessed to having drowned her children after drugging them with zopiclone. Autopsies only revealed a small amount of water in the lungs and stomach of the eldest. Toxicological analyses, including hair testing of the mother, were performed. Benzodiazepines, Z-drugs, neuroleptics and other sedatives were determined in peripheral blood, urine and hair by liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS). Zopiclone blood concentrations confirmed the massive intoxication of the two children (260 and 174ng/mL, respectively). Hair analysis showed very low concentrations of zopiclone in all segments (maximum 45pg/mg) in favor of regular exposure of the two victims during the 8 months preceding the deaths. The analysis of maternal hair confirms a regular exposure of z-drugs, as well as cyamemazine and amitriptyline.