The Syrian Observatory for Human Rights, which is based in Britain but gleans its information from a wide network of activists and medics on the ground, said Al-Nusra Front attackers also captured more than 100 regime soldiers.
"There were at least 100 dead on the regime side and 80 among the attackers, killed in clashes, bombardments and by mines," Observatory chief Rami Abdel Rahman said.
At least 120 soldiers were taken prisoner and about another 100 fled south in vehicles and on foot towards the town of Morek in the neighbouring province of Hama.
The jihadists advanced on the bases in coordination with Islamist rebel groups Ahrar al-Sham and Jund al-Aqsa, the Observatory said, adding that a string of villages in the area also fell.
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It was also another defeat for Western-backed rebels who were driven out of most of Idlib last month by Al-Nusra Front fighters.
Mainstream rebel forces had been battling to take Wadi al-Deif and Hamidiyeh for around two years, but failed to take it over despite repeated attempts.
Elsewhere in the war-torn country, regime warplanes hit the besieged district of Waer in the central city of Homs, killing at least 13 civilians, said the Observatory.
Among the casualties was a member of a delegation that had been in talks for a ceasefire with the government, as well as his wife.
Waer is the last rebel-held area of Homs, which as once known as the "capital of the revolution" against Assad.