"We've got a list of 20 guys, and it evolves," Niners general manager Terry Donahue said. "It evolves almost on a two- or three-day basis."
The Niners, who will be looking for help in the secondary, already have had safeties Roy Williams of Oklahoma, Tank Williams and Coy Wire of Stanford and Chris Hope of Florida State in for workouts.
Roy Williams is projected as perhaps the top safety available and is likely to be gone when the Niners pick No. 27 in the first round. But Tank Williams and Hope should be around in the early-to-mid rounds.
Cornerbacks Lito Sheppard of Florida and Chris Cash of USC also have been in for workouts, with Sheppard projected as a prime candidate for the Niners' first pick.
The Niners also have had top offensive line prospects Kendall Simmons of Auburn and Marc Colombo of Boston College in for workouts, along with Oregon State linebacker James Alllen.
Miami cornerback Mike Rumph and Georgia defensive end Charles Grant are among the prospects expected to work out for the team this week.