The United Nations said at least 50 people were killed on February 15 in attacks on five medical facilities and two schools in northern Syria.
Doctors Without Borders (MSF) said an air strike destroyed an MSF-supported clinic, killing at least seven people.
The attack in the northern town of Maaret al-Numan left eight people missing, presumed dead.
The Britain-based Syrian Observatory for Human Rights said Russian warplanes targeted the hospital.
In Aleppo Province, a missile struck a children's hospital in the town of Azaz, killing five people, according to the monitoring group.
A third air raid hit a school in a nearby village, killing seven and wounding others.
UN Secretary-General Ban Ki-moon called the attacks "blatant violations of international laws."
The violence comes despite world powers agreeing last week to a "cessation of hostilities."