Five monkeys who have been on the loose for five days found a "chink in the armour" of the security in their Edinburgh Zoo enclosure, keepers said.
The barbary macaques, which are not said to pose a threat to humans, made their bid for freedom on Friday.
The new primates from a centre in Germany, climbed a wall before squeezing under an electric fence.
Lorna Hughes, head zookeeper, said they were younger and more agile than macaques previously held in the cage.
Ms Hughes said she hoped attempts to lure them down with their favourite foods such as nuts, seeds and bananas would work before they were forced to use nets or, as a last resort, darts.
She told BBC Scotland: "We moved our 12 barbary macaques to a new enclosure within the zoo and, being inquisitive animals, they decided to explore their enclosure and found a certain little weakness where they could climb up a certain part of the wall and make their way under the electric fence at the top.
"So we have had a few who have been on a small holiday for a few days in the zoo.
"They have stayed within the vicinity of the enclosure just at the trees and path behind and we have known where all of the animals have been at all times.
"We have had barbary macaques living in this enclosure for many years, probably almost 20 years, but this is a new group who are a bit younger, more agile and they found a chink in the armour, which we are going to have modified."
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