Some cash machines on Thursday were still issuing the old 100-bolivar notes, hours before they expired.
President Nicolas Maduro said new higher-denomination bills would be fully distributed in January.
He has closed the borders with Brazil and Colombia until Sunday to stop "mafias" hoarding the currency abroad.
Venezuelans have been seen lining up outside banks after they were given 72 hours to exchange the 100-bolivar note for new larger denomination notes and coins.
The 100-bolivar note is worth just two US cents on the black market.
Some people on Thursday still received the 100-bolivar notes when they withdrew money at ATMs, then immediately had to queue up again to re-deposit the soon-to-expire notes.
"I don't get the joke," office worker Yarelis Carrero, who lives in the capital Caracas, told the AFP news agency. "When you withdraw cash at the ATMs, they give you 100-bolivar bills. And you can't get the new ones inside the bank, either."
Another bank customer said no-one had seen the new bank notes yet. "A guy I know who works for an armoured truck company said even they haven't seen them. Pure lies!" Saul Bernal said.
But President Maduro praised Venezuelans for their understanding in a televised address on Thursday.
"This is a big effort we're doing to tackle so many evils and tricks. We're burning the hands of the mafia," he said.
He said the new bills were already being distributed and would be fully circulated in January. However, the replacement bills have yet to be seen in the streets.
He also extended the border closure with Colombia and Brazil - in place since Tuesday - by another 72 hours.
Central bank data suggests there are more than six billion 100-bolivar notes in circulation, making up almost half of all currency.
The note is almost worthless so that buying almost anything with cash means a dangerous exercise carting around hundreds or thousands of bank notes in a country where robbery and violent crime is rife, says the BBC's South America correspondent Wyre Davies.
President Maduro has blamed currency speculators and gangsters in neighbouring Colombia for inflation that has reached 500%.
Economic experts, however, say the measure to take the note out of circulation will have little positive effect on the country's chronic economic and political problems.