Cynthia V. Kybal, daughter of Mrs. Elba Gomez del Rey de Kybal of Washington, D.C., and Byron Alexander Grant, son of Mr. and Mrs. William R. Grant of Oyster Bay, were married last Sunday at St. Dominic Church in Oyster Bay.

The bride was given in marriage by her uncle, Mr. Dalimil Kybal, who is assistant director of the Federal Preparedness Agency in this city. Deborah S. Grant, the groom's twin, was maid of honor and his brother, Gregory, the best man. Others included in the bridal party were the bride's brother, Alex Kybal and the groom's sisters, Melissa and Elise.

The bride and groom received master's degrees on May 21 from the Colgate Darden School of Business Administration at the University of Virginia. Mrs. Grant graduated from St. Timothy's School, and cum laude from Georgetown University. Her mother is a director at the Organization of American States and her father, the late Milic Kybal, was the senior economic advisor to the Inter-American Development Bank. Her grandfather, Vlastimil Kybal, served as Czechoslovak minister to Italy, Brazil, Argentina, Spain, Portugal, Mexico, and the Central American Republics; her grandmother, Anna Saenz, was a renowned Mexican painter.

Mr. Grant is a graduate of the Portsmouth Abbey School - of which he is a trustee - and Trinity College, Hartford. Before entering graduate school he was with Bankers Trust Company in New York and has now taken a position with W.R. Grace & Co., New York. Mr. Grant's father is vice-chairman of the Endowment Management and Research Corporation in Boston and was formerly vice-chairman of Smith, Barney, Harris Upham & Co., New York.