Stoic logic and in particular the work of Chrysippus (c. 279 – c. 206 BC) has only come down to us in fragments. To my knowledge the most accessible account is given in Sextus' Outlines of Pyrrhonism. Stoic logic certainly contained an axiomatic-deductive presentation of what we call today the 'propositional calculus'. The deductive system was based on both axioms and rules and appears to have been similar to Gentzen's sequent calculus. Certain accounts (by Cicero, if I am not mistaken) suggest that it included the analog of the 'cut rule'. There are tons of remaining questions. Was this propositional calculus classical or intuitionistic ? What type of negation did it employ ? Was it closer to relevance logics and many-valued logics or even to linear logic ? How did the Stoics treat modality ? What about the liar paradox ? How did they deal with quantification ? Was it in combinatory logic style or algebra of relations style ?