Stroh violin, or Strohviol, (Romanian: Vioara cu goarnă) is a trade name for a horn-violin, or violinophone—a violin that amplifies its sound through a metal resonator and metal horns rather than a wooden sound box as on a standard violin. The instrument is named after its designer, John Matthias Augustus Stroh, an 'electrical engineer' in London, who patented it in 1899. The Stroh violin is also closely related to other horned violins using a mica sheet-resonating diaphragm, known as phonofiddles.

In the present day, many types of horn-violin exist, especially in the Balkans.