Djibril Cisse put Lazio ahead from the penalty spot in the 35th minute before Lopes Wesley equalised before the hour mark.
Wesley put the visitors in front when he converted a 63rd-minute penalty after Luciano Zauri had brought down last man Mike Temwanjera in the area.
Zauri was shown a straight red card.
Giuseppe Sculli pulled the hosts level with 19 minutes remaining.
Sculli was first to test Vytautas Cerniauskas with his right-footed strike from the edge of the area kept out by the Vaslui goalkeeper.
Lazio almost took the lead in the 20th minute when Tommaso Rocchi got behind Cisse's cross only for his six-yard effort to be met by a fine save from Cerniauskas.
The hosts continued to press forward and were rewarded soon after.
The referee pointed to the penalty spot after Ionut Balaur had brought down Rocchi in the area.
Cisse placed the spot-kick into the upper left-corner to give his side a lead.
Cerniauskas denied Cisse soon after when he made a fantastic save with his feet to keep out the Frenchman's cross-shot from the right.
The visitors had their first chance before the break.
Martins Adailton's 30-yard effort towards the far post was saved by Lazio goalkeeper Federico Marchetti.
Lazio could have doubled their lead early in the second half had Cisse's right-footed strike from the edge of the area not gone just wide.
Vaslui got back on level terms in the 59th minute.
Wesley headed home a free-kick from Adailton and beat Marchetti.
The goal inspired the visitors, who took an unlikely lead four minutes later.
Zauri was handed his marching orders for hauling last man Tamwanjera to the ground.
Wesley sent Marchetti the wrong way to fire towards the right post for his second of the evening.
Lazio reacted and made it 2-2 soon after as Sculli's close-range header from Cisse's cross beat Cerniauskas.
The hosts were unlucky not to clinch three points with one minute remaining.
Substitute Libor Kozak's powerful header hit the crossbar with the keeper beaten as Lazio had to settle for a point.