Regeneration is a replacement effect that, when applied, performs three things: it taps the creature, removes it from all combat, and removes all damage marked on it — then the destruction event is replaced entirely (CR 701.15b). Deathtouch causes any amount of damage from that source to be considered lethal (CR 702.2c), but 'lethal damage' simply means the creature will be destroyed by state-based actions (CR 704.5g). State-based actions haven't resolved yet at the moment damage is dealt.
The key timing point is that state-based actions are checked after each game event, not during damage assignment. This means there is a window between damage being dealt and the creature actually being destroyed during which a regeneration shield can be activated or will automatically apply (CR 704.3). If a regeneration shield exists when the game checks state-based actions and would destroy the creature, the shield is used instead (CR 701.15b).
It does not matter whether the lethal damage came from deathtouch, combat damage exceeding toughness, or any other source — regeneration works the same way in all cases. Deathtouch has no special ability to bypass regeneration.
Concrete example: Your 2/2 creature is blocked by an opponent's 1/1 with deathtouch. Before state-based actions are checked, you activate your creature's regeneration ability (e.g., paying {G} for a creature with 'regenerate'). When state-based actions check, they see the creature should be destroyed, but the regeneration shield replaces that: the creature is tapped, removed from combat, and all damage is removed. It survives.
Unofficial fan resource — not affiliated with or endorsed by Wizards of the Coast. Answers are AI-generated estimates grounded in the Comprehensive Rules and are not a substitute for an official judge. Verify anything match-critical.