Embodiments of the present invention address deficiencies of the art in respect to nested transaction rollback and provide a method, system and computer program product for dynamic nest level determination for nested transaction rollback. In an embodiment of the invention, a nested transaction rollback method can be provided. The method can include detecting a violation of a block of memory accessed within a set of nested transactions, retrieving a tentative rollback level for the violation, discarding a speculative state for the block of memory at each level of the set of nested transactions up to and including the tentative rollback level, refining the tentative rollback level to a lower level in the set of nested transactions, and additionally discarding a speculative state for the block of memory at additional levels in the set of nested transactions up to and including the refined rollback level.