In a statement from its national office in Colorado, Gamma Phi Beta said it "regrets the e-mail sent regarding mandatory participation in a campus-wide blood drive and apologizes to the community, the Red Cross and campus."
The American Red Cross tells those who are sick or have recently received tattoos or piercings not to donate blood, both to protect the health of donors and to lessen the risk of transmitting diseases to recipients.
But sorority members at the University of Missouri-Columbia - a school that once set a world record for blood collection - were urged by a fellow member to lie about their health.
In an e-mail sent last Tuesday to about 170 members of Gamma Phi Beta, sophomore Christie Key, the chapter's blood donation coordinator, wrote: "I dont care if you got a tattoo last week LIE. I dont care if you have a cold. Suck it up. We all do. LIE. Recent peircings? LIE."
She added: "Even if you're going to use the Do Not Use My Blood sticker, GIVE ANYWAY." Donors who have second thoughts at the donation site can discreetly attach a sticker to a health questionnaire indicating their blood shouldn't be used.
Key declined to comment Monday and referred questions to Gamma Phi Beta's chapter president, who did not immediately return a call.
About 3,300 units of blood were collected at the Missouri event. The Red Cross reassured the public that its blood supplies are safe, saying all donations are routinely tested for safety.
Gamma Phi Beta's statement said the message was sent "without the consent or approval of any chapter officer."
Cathy Scroggs, a campus vice chancellor, said the university is investigating.
"I would characterize it at this time as one student that is overzealous," Scroggs said. "But we have heard that people have felt pressured to donate blood in the past, and this certainly has caused us to want to take a look at the whole process."
On a single day in 1999, the campus drive took in 3,156 units of blood - enough to earn recognition from the Guinness Book of Records as the largest single-site, single-day blood collection.
By Scott Charton