Relined culverts must be able to pass the design flood while meeting the necessary embankment freeboard condition. For inlet and outlet control culvert flow conditions, the discharge capacity of a slip-lined culvert is influenced by the geometry of the inlet end treatment. A number of factors including: reduced inlet flow area, the liner pipe wall roughness, and the inlet end treatment influence the relined culvert discharge capacity relative to the original culvert. To develop a better understanding of the influence of slip-lined culvert inlet end treatment geometry on discharge capacity, four different inlet end treatments associated with a thin-wall projecting host pipe and the segmental-lining culvert rehabilitation technique were evaluated experimentally. Inlet control head-discharge relationship and outlet control entrance loss coefficient trends were evaluated as a function of liner projection distance and liner-to-host pipe transition detail (sudden or tapered). The tapered projecting inlet was as much as 7% more efficient under inlet control and approximately 12% more efficient (entrance loss coefficient reduction) under outlet control, relative to the nontapered projecting inlet condition.