A record number of students are eligible for clearing compared to the same time last year.
The numbers, released by the university admissions service Ucas, will add pressure to disappointed A-level students facing an intense scramble to secure a place at university.
Clearing is available to students who failed to meet the grades required for their first choice of university and their insurance offer, as well as those who declined all their offers or did not receive any.
With universities increasing tuition fees from next year, competition for places is fiercer than ever and the clearing process is expected to last over the next few days.
Ucas said that by midnight last night there were 185,684 students eligible for clearing, compared to 180,632 at the same time last year.
Ucas added that the number of courses showing vacancies is 29,409 - a drop from 33,105 last year.
The service said that 56.4% of the 681,593 people who applied to start undergraduate university courses this autumn have been accepted so far - the same figure as last year.