LOS ANGELES (AP) _ After more than 16 months in preliminary hearings, the case of seven people accused of sexually abusing children at a preschool has already cost Los Angeles County $4 million, and attorneys say it has financially ruined at least five of the defendants.

Attorney Daniel Davis says his name also can be added to the list of economic casualties in the McMartin Pre-School molestation case.

The seven defendants are charged with multiple counts of molestation and conspiracy in the alleged sexual abuse of 14 students at the now-closed preschool in suburban Manhattan Beach.

Since authorities began investigating the case in July 1983, nearly $4 million has been spent for the investigation and prosecution, Municipal Court costs, court-appointed attorneys, the public defender's office, marshals and county clerk, said Dan Ikemoto, assistant county auditor-comptrolle r.

Without even knowing whether they will be tried, most defendants have already lost their life savings, homes, jobs, reputations, and in the case of two, their personal freedom, their lawyers said last week.

School founder Virginia McMartin, 78, has lost ''her life savings, her Manhattan Beach home, which was paid for, her interest in the property at the school and all other assets,'' said her attorney, Bradley Brunon.

''But the intangible costs are greater; a daughter and grandchild in prison or under a cloud of suspicion. The family has been through hell,'' he said.

Mrs. McMartin's granddaughter, 29-year-old Peggy Ann Buckey, lost her career as a teacher of handicapped children when she was named in the case, said her attorney, Deputy Public Defender Forrest Latiner. The two now live together in a small apartment with Ms. Buckey's father, Charles.

''There is no charge for my representation ... (but) the other emotional and financial costs are more than most people are asked to bear in a lifetime,'' Latiner said.

Ms. Buckey's mother and brother, Peggy McMartin Buckey and Raymond Buckey, have been in jail for nearly two years. Mrs. Buckey is basically indigent and her home and school were sold to pay legal costs for herself and son, said her attorney, Dean Gits.

''And how can you calculate the loss of freedom for almost two years?'' Gits added.

The McMartin Pre-School is now owned by Davis, Raymond Buckey's attorney, who says he has lost his house, his secretary and his Beverly Hills penthouse office because of the extensive time he's devoted to the case.

He said Municipal Court Judge Aviva K. Bobb, presiding at the hearing to determine if there is enough evidence to warrant trial, has refused to grant him court-appointed status, in which the county would pay his legal fees. Davis could not be reached for comment on Raymond Buckey.

Defendant Betty Raidor, according to her attorney, Walter Urban, has lost more than $200,000, including her life savings and her Manhattan Beach home.

Attorneys for defendants Mary Ann Jackson, 58, and Babette Spitler, 37, could not be reached for comment.

The preliminary hearing began in June 1984 for Raymond Buckey and was consolidated with that of the other defendants in August 1984.

The prosecutors finished presenting their case in October after calling 14 of the child witnesses named in the criminal complaint. Mrs. Bobb has dismissed two-thirds of the charges because prosecutors didn't call witnesses to support them.

The defense began presenting its case last month, and Bobb last week rejected requests for a delay, ruling the defense, by not having a witness ready, had rested. A pediatrician who testified there was evidence of molestation in 10 of the alleged victims is to be cross-examined Jan. 7.