At least 22 migrants, among them 13 children, drowned overnight when two boats sank off the islands of Kalymnos and Rhodes, the Greek port officials said on Friday.
The latest drownings prompted a sharp response from Greek Prime Minister Alexis Tsipras who said he felt "shame" over Europe's failure to prevent the tragedies.
Another 138 people were pulled to safety although the coastguard were continuing their search for survivors, officials said.
Off Kalymnos, authorities recovered 19 bodies on Friday morning, among them six women and 10 children.
Further south, a woman, a child and baby drowned when another boat sank off Rhodes. Three people who had been on board with them were still missing early Friday, while six others were rescued.
And early on Friday, an AFP correspondent saw another boat foundering off the coast of Lesbos, with a group of desperate people perched on the roof screaming for help.
The latest deaths came after a string of drownings off the tourist islands of Lesbos and Samos on Wednesday, with the latest figures showing at least 17 people, including 11 children, died.
Throughout October, 68 people have drowned while trying to reach Greece from Turkey, according to an AFP count based on statistics released by Greek port authorities.
Faced with yet another "humanitarian tragedy", Tsipras said it was crucial to prevent the Aegean Sea from becoming a graveyard for people fleeing war and misery and seeking safety in northern Europe.
"As a European leader, I feel shame over Europe's inability to defend its values," Tsipras told the Greek parliament.
"Our first duty is to save lives and not to allow the Aegean to become a cemetery... for that we are not asking for even a euro" from our European partners, he said.
He also underlined the urgent need of having Turkey "respect its commitments" to halting the flow of people leaving its territory by boat and stressing Athens' willingness to be "a link between the EU and Turkey" on the matter.
With the winter weather whipping up gales and worsening conditions at sea, the UN refugee agency (UNHCR) said there was an "urgent need" to strengthen search and rescue capacity in the area.
"We have warned for weeks that an already bad situation could get even worse if desperate refugees and migrants must continue to resort to smugglers who send them out to sea despite the worsening weather," said Alessandra Morelli, UNHCR's Senior Operations Coordinator for Greece in a statement released on Thursday.
"Our fears are now being realised. Nearly every day now we are seeing children, parents, the elderly and the young dying as they try to reach Europe."
Since the start of the year, 560,000 migrants and refugees have arrived in Greece by sea, out of over 700,000 who have reached Europe via the Mediterranean, according to the International Organization for Migration (IOM).
More than 3,200 people have died during the perilous crossings although most of the deaths have occurred on the longer sea route from Libya to Italy.