"Bring them home, bring them home," the crowd chanted at several points during the one-hour rally.
"She just needs the help of our government," said Lisa Ling, Laura's sister and a fellow journalist. "Only through the government does she have the hope of being released."
Lee, 36, and Laura Ling, 32, reporting for Current TV, were at the border of China and North Korea on March 17 to report on trafficking of women there when they were arrested by North Korean police and propelled into the international spotlight.
Ling and Lee were convicted of illegally crossing into North Korea by that country's highest court last month and sentenced to 12 years of hard labor.
After weeks of hoping that keeping a low profile would help bring the two home, Ling's family has changed strategy in recent days, launching a media offensive.
In addition to Thursday's rally, Lisa Ling has conducted local and national interviews, and supporters have launched a Web site, www.lauraandeuna.com/.