Fifteen people were killed on Sunday when a suicide bomber blew himself up in a crowd of people seeking to join the Yemeni army in the south-eastern city of Mukalla, medical officials said.
The attack took place as army recruits gathered at the gates of a barracks in the city, where pro-government forces and allied Gulf troops took control last month after the withdrawal of al-Qaeda militants who had occupied it for a year.
The Islamic State extremist group claimed responsibility for the attack, according to the US-based SITE Intelligence Group which monitors jihadist activity.
About 30 more people were injured in the blast, according to the officials, who spoke on condition of anonymity.
At least seven people were killed on Thursday in an attack, claimed by the Islamic State extremist militia, on an army compound in the city.
Al-Qaeda's Yemeni branch, seen as one of the international jihadist network's most dangerous local affiliates, has also vowed to attack Yemeni government forces and members of the Gulf-led alliance backing them.
Representatives of the Yemeni government and mainly Shiite Houthi rebels, who control much of the north of the country including the capital Sana'a, are currently engaging in difficult UN-brokered peace talks in Kuwait City.