Vertical sense devices in vertical trench MOSFET. In accordance with an embodiment of the present invention, a semiconductor device includes a main vertical trench metal oxide semiconductor field effect transistor (main-MOSFET). The main-MOSFET includes a plurality of parallel main trenches, wherein the main trenches comprise a first electrode coupled to a gate of the main-MOSFET, and a plurality of main mesas between the main trenches, wherein the main mesas comprise a main source and a main body of the main-MOSFET. The semiconductor device also includes a sense-diode. The sense-diode includes a plurality of sense-diode trenches, wherein each of the sense-diode trenches comprises a portion of one of the main trenches, and a plurality of sense-diode mesas between the source-FET trenches, wherein the sense-diode mesas comprise a sense-diode anode that is electrically isolated from the main source of the main-MOSFET.