Tomorrow is the seventh annual International Left-handers Day. Among the organization's requests: Shake hands with your left hand.

Other rights for lefties:

* Left-handers International (8,000 members), 3601 Southwest 29th St., Topeka, Kan. 66614. (913) 273-0680. Dues: $18 (includes bi-monthly magazine, Lefty). LI provides new members with a list of several dozen stores and mail-order firms catering to left-handed equipment--from can openers to musical instruments.

* Sinistral Sig (Mensa--high IQ--group for lefties). For information: Sharlene McEvoy, editor, The Sinistralian (bimonthly newsletter), 200 Emmett Ave., Derby, Conn. 06418. (203) 735-1759. Dues: $2.25.

* National Association for Left-handed Golfers (1,100 members). Ken Ahrens, 10149 Hammerly #714, Houston, Tex. 77080. (713) 464-8683. Dues: $15 (includes monthly newsletter). Next annual tournament: June 1984 in Dallas/Ft. Worth.

* Left Hand Guitar Shop. Tom Turrisi, 6615 Backlick Rd., Springfield, Va. 22150. Mandolins, guitars, electric basses. Catalogues, $1.

* The Left Bank, Joan U. Upshaw, 10235 Warwick Blvd., Newport News, Va. 23601. Retail shop. Mail-order catalogue, 40 cents postage.

* Southpaws, Ltd. Mail order, 100 items of southpaw supplies. Run by special-education teacher Barbara Schwindt, 10556 Jason Lane, Columbia, Md. 21044. Catalogue (available in September), $1.