Muhammad Shamr, a member of the ruling Popular Congress party, was shot in his car early on Wednesday morning in the capital, Sanaa.
Yemeni police said that the attack took place just after midnight in the southern quarter of the city and that his vehicle was hit repeatedly by automatic weapon fire.
Shamr was elected to represent the village of Maghrib Ans in Dhamar province and also sat on the government's Public Health Committee (PHC) as a qualified administrator and pharmacist.
His only business interests appear to be linked to a hospital he owned in Dhamar, the Dar al-Shifa.
However, Aljazeera has learned that two other people were injured in the attack, which may have been linked to a dispute with his neighbours.
Nevertheless, the PHC's chief, Dr Najib Ghanim, told Aljazeera.net that he was shocked by the killing and said he could think of no reason why anyone would want Shamr dead.
"This was shocking and totally unexpected, we need the police and government to get to the bottom of this crime", he said.
The assassination led to calls from other government officials for a full investigation and police say they have already arrested two people who they believe were involved in planning the attack.
Meanwhile, the Popular Congress party has asked some six lawmakers, headed by the country's security council chief Muhammad al-Hawari, to form a committee to investigate the killing.