Inthisarticle,wepresentaclassificationof2-designswithprimereplicationnumbers admitting flag-transitive automorphism groups. In conclusion, if G is a flag-transitive automorph- ism group of a 2-design D with prime replication number, then G 6 AΓL1(q), or D belongs to five infinite families of 2-designs or it is (isomorphic to) one of eight sporadic examples.