Parents from as far away as California, New York and Canada said they were kept from entering a half-hour before the graduation Sunday afternoon, The Atlanta Journal-Constitution reported.
Some said they didn't know the doors would be locked 30 minutes before the ceremony in Atlanta.
"I can't put into words how upset I am," said Melvin Cox of Oakland, Calif., who missed his only child's graduation.
Cox said he flew in from California and arrived at Spelman on 2:30 p.m. Sunday, but was barred from entering for the 3 p.m. ceremony.
"Not to be allowed to attend your child's graduation is unconscionable," he said.
Some of the parents said they thought some leeway should have been given due to rainy weather and traffic delays as streets were blocked for President Barack Obama's motorcade. The president was speaking at the Morehouse College commencement.
The doors were locked as part of the safety measures for the event, Spelman said in a statement. School officials expressed regret that some guests missed the event, but said the guidelines were communicated throughout the school year.
"There are guidelines and protocols in place as safety measures and for optimal event facilitation, including no access to the facility after a certain time, and no exit and re-entry," Spelman said in the statement.
Belinda Robinson from San Francisco said about 150 people were kept from entering the ceremony.
"I am very upset. My heart is broken," she said. "This is for my daughter. I wanted her to really enjoy the experience. This crushed her."
Cox said some of the parents hoped to meet with Spelman President Beverly Daniel Tatum on Monday to discuss what happened.
Spelman calls itself the nation's oldest historically black college for women. It was founded in 1881 as the Atlanta Baptist Female Seminary. It became Spelman College in 1924.
Information from: The Atlanta Journal-Constitution.
Copyright 2013 The Associated Press.