Ethchlorvynol is a sedative and hypnotic drug. It is been used to treat insomnia but has been largely superseded and is only offered where an intolerance or allergy to other drugs exists.

Along with expected sedative effects of relaxation and drowsiness ethchlorvynol can cause skin rashes, faintness, restlessness and euphoria. Early adjustment side effects can include nausea and vomiting, numbness, blurred vision, stomach pains and temporary dizziness. An overdose is marked by confusion, fever, peripheral numbness and weakness, reduced coordination and muscle control, slurred speech, reduce heartbeat.

It is addictive and after prolonged use can cause withdrawal symptoms including convulsions, hallucinations and memory loss. Due to these problems it is unusual for ethchlorvynol to be prescribed for periods exceeding seven days.

It is a barbituric acid, the systematic name of ethchlorvynol is usually given as ethyl 2-chlorovinyl ethynyl carbinol or 1-chloro-3-ethyl-1-penten-4-yl-3-ol. Its empirical formula is C₇H₉ClO. In the United States it is sold by Abbott Laboratories under the tradename Placidyl.