After the 26-year-old star avoided the many rehab-related questions Letterman asked her, the host took a moment from grilling the actress with uncomfortable questions to praise her for her strength.
"We never thought we'd see you again," Letterman told Lohan. "But yet you have enough spine, enough sense of yourself enough poise to come out here and talk to me."
Lohan then teared up, smiled and took a sip from Letterman's mug before putting it down quickly.
"I thought this was Vodka," she joked later adding "I love seeing you."
"I love seeing you, honestly, " Letterman responded handing her a tissue.
Letterman seems to have an uncanny ability to make young stars shed tears. In a recent interview with Selena Gomez, the "Late Show" host admitted to having made Justin Bieber cry.