Sharp　transitions　in　structure　stiffness　and/or　ground　properties　have　a　significant　influence　on　the　seismic　response　of　tunnels.　These　issues　are　not　well　understood　yet,　or　at　least　not　well　considered　during　design.　An　analytical　solution　is　derived　to　investigate　the　seismic　response　of　long　tunnels,　built　in　non-homogeneous　ground,　subjected　to　sinusoidal　shear　motions.　It　is　assumed　that　the　tunnel　is　excavated　in　two　different　soil　deposits　that　have　a　sharp　contact,　and　there　is　a　transition　zone　through　the　contact.　It　is　also　assumed　that　the　tunnels　can　be　represented　as　beams　on　an　elastic　medium.　Continuity　at　the　contact　between　the　different　contact　sections　of　the　tunnel　is　imposed　to　solve　the　governing　equations　of　equilibrium.　In　addition,　wave　passage　effects　along　the　tunnel　are　considered　by　including　a　phase　angle　in　the　far-field　displacements.　Explicit　formulations　are　obtained　for　tunnel　deflection,　bending　moments　and　shear　forces.　The　solution　is　verified　by　providing　comparisons　between　its　results　and　those　from　the　Finite　Element　program　ABAQUS.　A　parametric　analysis　is　presented　where　the　effects　of　the　stiffness　of　the　structure,　the　shear　velocity　of　the　soil　and　the　length　of　the　transition　zone　are　investigated.