A UK-based Syrian Observatory for Human Rights said on Tuesday that ISIL beheaded the two women and their two husbands after accusing them of using "magic for medicine".
It is not known what non-traditional health remedy the two couples had sought.
The Observatory's chief, Rami Abdel Rahman said "It is the first time that the beheading of women, by the use of sword in public, has taken place in Syria."
The bkilling took place in the city of Deir Ezzor and the city of Mayadin. ISIL beheaded the first couple on Sunday and the second couple on Monday.
ISIL reportedly covered up both women and beheaded them, with many people watching.
