Jordan has sent Syrian refugees, including wounded civilians and unaccompanied minors, back across the border in violation of international responsibilities,
The New York-based monitor issued a statement accusing Jordan of ignoring long-accepted principles forbidding governments from returning people back to areas where their lives may be in danger.
There was no immediate response from officials in Jordan, now home to more than 600,000 Syrian refugees.
The report, based on interviews with Syrians and aid workers, marks the latest in a series of allegations that Jordanian officials have sent vulnerable refugees back to Syria or closed the border to those fleeing violence.
"What's new here is the categories of people being deported are even more vulnerable," Nadim Houry, deputy director of Human Rights Watch's Middle East and North Africa division, said in a telephone interview. "In this case, we're talking about wounded and unaccompanied minors."
The difficulties facing Syrian refugees in Jordan, aid workers say, are part of a larger trend across the Middle East. More than 3 million people have fled Syria since the conflict broke out in 2011, the U.N. says, with the great majority settling in Jordan and other neighboring nations, including Lebanon, Turkey and Iraq.
"We're hitting the point where host countries in the neighborhood are becoming more hostile, with increasing tensions in host countries," Houry said. "The doors are narrowing for Syrians."
Jordan opened up informal humanitarian corridors in 2011 along its more than 200-mile border with Syria, providing safe passage for refugees.
Many Syrian refugees arriving in Jordan are sent to the cramped confines of the Zaatari camp, seven miles from the Syrian border, while others settle in Jordanian towns and cities, often joining relatives.