Benita Charles and Erzulia Frederic wore smiles and corsages yesterday as they left a federal prison in Alderson, W.Va. They were the first of 52 Haitian women there to be released after 10 months' detention for entering the United States illegally.

All of the women will be released in small groups over the next few weeks in compliance with a federal court ruling last June ordering the U.S. Immigration and Naturalization Service to free over 1,500 Haitians detained as illegal aliens in 14 centers around the country.

So far, about 350 of those Haitians have been released, according to INS officials.

Like most of the Haitian women at Alderson Federal Correctional Institution, the nearest holding center to Washington, Erzulia and Charles entered the United States last September after leaving their Caribbean Island home.

The two women, both 27, flew to Miami yesterday after signing a document promising to appear at a hearing before Immigration authorities that will determine whether they can remain in the United States.

All the detained Haitians are being released into the care of volunteer church agencies that find them sponsors, usually a relative. Both the sponsor and the church agency must also sign the document guaranteeing that the Haitians will show up at the hearing. In addition, the Haitians, who have all applied for political asylum, must report weekly to the church agency. While awaiting their hearings, they are allowed to work.

Though the women held at Alderson were not convicted prisoners, they were subject to the rigors of prison life and regulations. Boredom, a sense of isolation and an inability to speak English often caused tension between the Creole-speaking women and prison authorities. On two occasions the women went on hunger strikes to protest their prolonged detention.