Hiccup is a sudden contraction of the inspiratory muscles, followed by an abrupt closure of the glottis, thus producing a characteristic sound. In the literature, some drugs have been reported to induce hiccup. We discuss three case reports after administration of benzodiazepine to healthy young subjects during two clinical trials. In the first study (a bioequivalence trial of two forms of lormetazepam, tablets and oral solution), 12 subjects were included in an open controlled crossover study with two periods separated by a washout of 7 days. Two subjects presented with hiccup after administration of lormetazepam (2mg oral solution). The symptom resolved in 10 and 40 minutes, respectively. In one subject, rechallenge with a tablet of lormetazepam was positive. The aim of the second study was to assess the effect of sleep deprivation and lorazepam-induced sedation on saccadic eye movements in 12 healthy subjects. Hiccup occurred in one subject 3h 15 after administration of a single oral dose of lorazepam (2mg) and resolved in 45 minutes. All cases were evaluated according to the French imputation method. These observations are discussed with regard to the drug classes mentioned most frequently in the literature.