Every recorded result
shownNaruto · ch. 345Confirms the ladder
Itachi Uchiha beat Orochimaru in Naruto.
Flashback: Orochimaru tries to take Itachi's body while both are in Akatsuki, is caught in a genjutsu and loses his left hand.
shownNaruto · ch. 392Confirms the ladder
Itachi Uchiha beat Orochimaru in Naruto.
A sealing: the Totsuka blade closes over Orochimaru as he emerges from Sasuke.
What each of them is ranked on
2 wins · Itachi Uchiha · rank 8
classic · shippuden
Joint holder of the largest figure the books ever issued, and he does not survive to meet anything in the tier above him. The record supports the number as far as it goes — a complete Susanoo, a genjutsu nobody counters honestly, and a fight against his own brother that he loses on purpose while dying of an illness. What it cannot do is compare him to opponents who arrived after the book went to print.
statedNaruto Databook 3 · 2008
Rated 35.5 of a possible 40, the joint highest total published.
shownNaruto · Sasuke and Itachi arc
Fights Sasuke using Susanoo and dies at the end of the encounter. — 2008
0 wins · Orochimaru · rank 10
classic · shippuden
Graded 35 of 40, half a point off the top, with an on-page record of losing — to Hiruzen at a cost, to Itachi immediately, to Sasuke from the inside. What keeps him this high is that none of the defeats stuck: the man's actual technique is not winning fights but declining to stay dead, and he is still present and operating long after most of the names above him are gone.
statedNaruto Databook 3 · 2008
Rated 35 of a possible 40.
shownNaruto · Konoha Crush arc
Fights Hiruzen Sarutobi and survives at the cost of his arms. — 2001
What this does not settle
2 results, each cited, and the tally counts every one of them the same. That is its rough edge: a win at one side's lowest weighs as much as a win at its peak, which is why a level score goes to the latest result rather than to a judgement about which fight mattered. It is a record of meetings, not a ranking of its own.
The ladder above it is argued from everything either of them has been shown doing; this page is argued from these 2 citations.
Where the two disagree, the disagreement is the point, and it stays visible rather than being resolved by whichever of them happens to be on this page.