The Rams, widely tipped to go straight back down, more than held their own and thoroughly deserved to take a point from their first game back in the top flight for six years.
Matt Oakley gave Derby are early lead, but Portsmouth hit back with goals from Benjani Mwaruwari and John Utaka, before Andy Todd equalised with a flying header.
Both teams could have won the game late on, but the draw was a fair result and Derby will be satisfied to have opened their campaign with a point.
It was Derby that had started brightly with Steve Howard flicking-on a goal kick to send Oakley in on the left to drive a low shot past David James.
Portsmouth were struggling to get into the game as Oakley and Todd, playing in a holding midfield role, dominated possession, but the visitors gradually imposed themselves and the equaliser came in the 26th minute.
Utaka slipped the ball inside to David Nugent, who played Benjani in and the striker turned inside Andy Griffin to fire a low shot under Stephen Bywater.
Howard almost restored Derby's lead with a header that struck James' left-hand post and County could have gone in front early in the second half.
A loose ball from Sulley Muntari was pounced on by Craig Fagan and the midfielder raced clear, only for James to block his shot and Sol Campbell tidied up.
As the game began to open up, both sides were finding gaps to exploit and it needed a perfectly-timed challenge by Pedro Mendes to deny Tyone Mears in the 75th minute.
Portsmouth looked to have won it seven minutes from the end when Sylvain Distin swung over a free-kick and Hermann Hreidarsson headed the ball down for Utaka to score with a low right-foot shot.
But Derby hit back straight away when substitute Gary Teale went past Hreidarsson and Todd threw himself full-length to head into the net.