Zoe Caldwell's 'Medea,' a theatrical mountaintop; Medea Tragedy by Euripides, freely adapted by Robinson Jeffers. Starring Zoe Caldwell. Directed by Robert Whitehead.

Up to last week, Broadway's grand dramatic summits this season consisted of ''Nicholas Nickleby,'' ''The Dresser,'' and ''Othello.'' Now add one more mountaintop -- ''Medea,'' at the Cort Theater, with Zoe Caldwell scaling the histrionic heights as the hate-maddened antiheroine of Euripides's tragedy.

Although one of the most popular plays from the alien world of Greek tragedy, ''Medea'' presents special problems for a latter-day audience. Oedipus, after all, didn't realize that he was committing patricide and, ultimately, incest. However, given her extreme emotional disarray, Medea knows what she is doing at every step. James Agate, the British critic, dismissed her curtly: ''That cruelty turned her into a vile thing is not the fault of cruelty, but of the degenerative metal upon which it was exercised. Medea was essentially not noble, but base.''

Was Medea ignoble and base or was she rather a primitive (a ''barbarian,'' as she scornfully proclaims), a woman totally ruled by extremes of passion? For love of Jason, whom she helped win the golden fleece, Medea betrayed her father, killed her brother, and ''made my own land hate me forever.'' For hatred of the now unfaithful Jason, Medea wreaks incendiary vengeance on his young bride and her father, Creon, and slays her own two little boys. The bottom line of Medea's motivation is reached in her explanation to their distraught father: ''I have done it: because I loathed you more than I loved them.''

To make such a woman -- pulled down ''to this hell of vile thoughts'' -- believable requires exceptional resources of the player's art. Miss Caldwell brings them all to bear in the revival staged by her husband, Robert Whitehead. In her performance are the guile and cunning, the fierce strength springing from weakness, the deep hurt and sorrow, the readiness to use her witchcraft for vengeful ends.

Her dark-skinned Medea is as dangerous and unpredictable as a subterranean fire, an impression heightened by the almost choreographic nature of her movements. It is as the outsider, the foreigner, the woman facing banishment and fighting alone against the might of Corinth, the discarded ''instrument'' of Jason's success, that Miss Caldwell manages to command the spectator's understanding of this jealousy-maddened creature.

Judith Anderson, for whom Jeffers wrote the adaptation and who played Medea in the original 1947 production, returns now to endow with noble strength and compassion the role of the Nurse. Mitchell Ryan's middle-aged, power-conscious Jason is a plausible climber, the one-time varsity hero now angling for a place in the executive suite. The Creon of Paul Sparer is an arrogant dictator whose momentary yielding to Medea's supplication proves fatal. Pauline Flanagan, Harriet Nichols, and Giulia Pagano, looking like figures from a Greek frieze, are eloquent intermediaries. A fine cast includes Peter Brandon (Aegeus), Don McHenry (the Tutor), and Jason Kimmell and Christopher Garvin (the Children).

Ben Edwards's lofty setting -- an arrangement of stairs dominated by the massive facade of Medea's house - has been meticulously lighted by Martin Aronstein. Jane Greenwood's graceful costumes enhance the visual beauties of the production. Composer David Amram's incidental effects - flutings, pipings, and percussion - evoke a sense of old, forgotten, far-off things. Count ''Medea'' a theatrical event in the grand tradition. In other words, a summit.