Piston-ring friction accounts for a substantial portion of engine friction. The performance of piston rings also affects many aspects of engine performance such as oil consumption, blowby and wear. Because of the complexity of the piston-ring and cylinder-bore interface, the comprehensiveness of piston ring analysis has historically lagged behind that of other engine components. This paper describes a recently developed lubrication analysis of the piston-ring pack. The new analysis improves upon existing analyses in several areas, and it includes two models. The simpler model includes only fully flooded lubrication analysis. The more comprehensive model considers the effects of lubricant starvation and includes the lubricant transport on the cylinder bore. Applications of these analytical methods to evaluate the effects of design parameters are also presented.