SAN FRANCISCO (AP) _ Five years after black parents won a statewide ban on using IQ tests to assess their learning-disabled children, a second group of minority parents is suing to bring the tests back.

The original litigants say the tests are culturally biased and resulted in huge numbers of black children being misclassified as retarded.

The new plaintiffs, backed by the conservative Landmark Legal Foundation of Kansas City, Mo., say the black-only ban is discriminatory and denies black parents the option of having their children tested.

The new case was sparked when Mary Amaya was told her mixed-race son could be tested if she re-registered him as Hispanic, rather than black, said Landmark lawyer Peter Hutchison.

Earlier this month, some parents won a preliminary ruling allowing them to arrange testing for their children. The lawsuit has not yet gone to trial.

Education Department lawyer Barry Solotar said state officials are considering how to respond to the July 15 ruling. One option would be to ban tests for all races, which would knock the props from the discrimination claim.

The case is being followed closely by national activists, who considered the Califonia ruling a landmark decision.

In 1979, U.S. District Judge Robert Peckham prohibited the use of IQ tests for diagnosing blacks as retarded or placing them in classes for the retarded. In 1986, he further forbade the use of IQ tests to identify blacks as learning-disabled or to assess blacks who had already been assigned to special education classes.

The current lawsuit charges that second order was improper.

If the ban is repealed, ''they will use these tests once again for deciding black children are not competent intellectually to do regular work. They'll put them in classes where they will get an inferior education and they will fall further and further behind,'' said Monty Neill, associate director of FairTest of Cambridge, Mass., a leading critic of standardized tests.

Blacks represent 16 percent of the nation's public school students but 37 percent of those labeled retarded, according to 1987 statistics from the U.S. Office of Civil Rights.

Critics say the tests are grounded in white cultural values and are a poor tool for diagnosing other children.

For instance, Neill said, the commonly used revised Wechsler Intelligence Scale for Children asks what should be done for a cut finger. Children get two points for responding ''put a Band-Aid on it,'' one point for ''go to the doctor (hospital)'' and no points for ''suck blood ... don't panic.''

Minority children usually pick option two, Neill said, and a study found that was because the children assumed ''cut'' meant a big cut.

''The cultural assumption was, in effect, if some stranger's going to ask me about a cut it must be pretty bad,'' he said.

Supporters of such tests maintain that a standard measure is necessary to evaluate children.

''Nothing you have is culture-free. You try to look at something that's culture fair,'' said Loeb Aronin, director of psychological services for the Los Angeles school district.