Tribal sources said the unmanned aircraft, which only the United States operates in the region, targeted a car carrying four militants in the southern province of Shabwa, a stronghold of the jihadist network.
A similar strike on a car on Monday in a desert area between Shabwa and the neighbouring province of Marib killed three suspected members of Al-Qaeda.
That vehicle was hit by four missiles.
The previous day US President Barack Obama had vowed no let-up in Washington's campaign against jihadists in Yemen.
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Obama ruled out US troop deployment in Yemen but said Washington would continue "to go after high value targets inside Yemen", admitting however that this was "a long, arduous process".
According to the New America Foundation, the United States has carried out more than 110 strikes on targets in Yemen since 2009, mostly using drones.
One such attack in September 2011 killed US-Yemeni cleric Anwar al-Awlaqi, a leader of Al-Qaeda in the Arabian Peninsula accused of instigating a string of attacks against the United States.