Anthony I. (Tony) Janulewicz, 46, a part-owner of several restaurants in Washington and Ocean City, Md., died Monday at George Washington University Hospital. He had cancer.

Mr. Janulewicz was born in Springfield, Mass. He served in the Army in Europe in the early 1950s and then returned to Springfield, where he graduated from American International College there. He earned a law degree from New York University and was attorney with the consumer protection division of the Federal Trade Commission in New York from about 1960 until 1967, when he moved to the Washington area.

By that time, Mr. Janulewicz already was in the restaurant business here with one of his brothers, Stanley. In 1965, they opened the Cafe Polonaise on Connecticut Avenue NW. Their next venture was the Robin Hood Restaurant near 14th and K streets NW. In 1968, they opened The Attic on I Street NW, one of the first discos in the Washington area. They also opened Janl's on 20th Street NW.

In the same period, the Janulewicz brothers opened the Sazarac Sea Pub and the King's Dungeon restaurants in Ocean City. They also started an Attic disco in Mays Landing, N.J., which now is operated by another brother, Joseph.

About two years ago, Tony Janulewicz designed and built the Bayside Skillet Restaurant in Ocean City. Since then, he had disposed of his interests in his other restaurants in Washington and Ocean City.

In December 1976, the Washingtonian Magazine named Mr. Janulewicz as one of "77 people to watch in "77."

In addition to his brothers, Stanley, of Ocean City, and Joseph, of Mays Landing, N.J., Mr. Janulewicz's survivors include his wife, Rebecca, of the home in Ocean City; two children, Matthew and Jennifer, also of the home; another brother, William, of Springfield, Mass., and three sisters, Josephine Borys and Mary Glica, both of Springfield, and Helen Robinson, of Albany, N.Y. CAPTION: Picture, ANTHONY I. JANULEWICZ