Lee Kun-Hee, 70, is facing legal action from Lee Maeng-Hee, 80, over shares reportedly worth 700bn Korean won (£396m).
The dispute centres on eight million shares in Samsung Life Insurance, along with 20 shares in Samsung Electronics that the brothers inherited from their father when he died in 1987.
Maeng-Hee has accused his brother of keeping the shares for himself. His legal filing says that the stocks were assets "put in a trust under the name of non-heirs, and they should have been apportioned to the heirs according to law".
Their father, Lee Byung-chull, founded Samsung in 1938 as a trader of noodles and groceries, before rapidly expanding the business after World War II.
The Samsung Group now covers electronics, shipbuilding, telecoms and construction, with a combined turnover of $220bn in 2010.
Last month, Samsung Electronics posted a 17% rise in profits in the last three months of 2011, buoyed by strong growth in its mobile phone sales.
According to the Forbes Rich List, Lee Kun-Hee was the richest man in South Korea in 2010 with a personal fortune of $7.9bn.
It was unclear why the elder brother has decided to file the lawsuit at this time, and Samsung has not commented on the action.
Meanwhile, Samsung said today that it is considering various options to improve the fortunes of its loss-making LCD flat screen TV business, amid reports that a sale or spinoff of the unit is on the cards.
The firm recently ended its liquid crystal display (LCD) joint venture with Sony Corporation as global demand for flat-screens weakened sharply due to rising competition from China and dwindling sales.
Most manufacturers, including Samsung, are shifting to a newer type of flat-screen display called organic light-emitting diode (OLED), which is currently being used in high-end smartphones and is expected to become standard in flat-screen TVs in the future.
The Chosun Ilbo today published an un-sourced report claiming that Samsung was considering spinning off its LCD business, which suffered more than 1tn won in operating losses in 2011.