Experimental studies covered risk of possible toxic influence by medications - derivatives of 1.4-benzodiazepine - in single and multiple intake by intragastric way, inhalation and skin application. The authors give recommendations on hygienic regulation of 1.4-benzodiazepine derivatives - alprazolam, diazepam, mezapam and nozepam. The study results served as a base for specifying approximate safe level of exposure to alprazolam at level of 0.1 mg/m³, diazepam - 0.2 mg/m³, mezapam - 0.3 mg/m³ and nozepam at level of 1.0 mg/m³ in the air of workplace.