REP. PETER RODINO has won the Democratic primary in his race for a 20th term in the House of Representatives. That's not very surprising, except that most voters in his New Jersey district are black and he had a black opponent. This is the eighth primary Mr. Rodino has won in his district since it got a black majority in 1972.

This race was noteworthy mostly for the appearances of Jesse Jackson for Mr. Rodino's opponent, Newark councilman Donald Payne. "In the history of New Jersey, there has never been one black congressman," Mr. Jackson said. "That's not fair."

Unfair to whom? To the voters? Surely they are capable of deciding for themselves who will most fairly represent them. Mr. Rodino's voiting record and his service for constituents go back to a time long before he could have dreamed of having a black-majority district and have always shown great sensitivity to blacks. As chairman of the House Judiciary Committee, he has been a national leader of competence and integrity, and he is in a key position on all civil rights issues.

Certainly in the past black politicians were defeated or deterred from running because whites would not consider voting for them. But that is much less the case today. Blacks have been elected to the House from majority-white districts ranging from Atlanta to Kansas City to Berkeley, Calif., and black mayors have been elected in white-majority cities, including Los Angeles, Chicago, Philadelphia and Cleveland. On the same day Mr. Rodino was renominated, Democratic voters in Mississippi -- Mississippi! -- chose a black over a white for the state Supreme Court.

We would like to see more black candidates, and not just in black-majority constituencies. Mr. Jackson's formula -- blacks should vote for blacks -- will produce only the most marginal increases in the number of black officials, since most such constituencies are represented by blacks already. Surely he would not argue that whites should vote only for whites in white-majority constituencies. Greater increases will come as more and more voters become willing to consider all candidates fairly and to make their choices regardless of race.