Internal turning or boring operation is a common metal working process that is usually associated with vibration problems. The vibration problems in internal turning considerably influence important factors such as surface quality, productivity, production costs, etc. In order to gain further understanding of the dynamic metal cutting process, an important early step is to thoroughly classify the vibrations. Boring bar vibrations have previously been proven to be nonstationary when analyzed with traditional methods. For vibrations originating in a combination of a rotating workpiece and random material inhomogeneities, it can be anticipated that the vibrations have cyclostationary properties. Methods for analysis of cyclostationary signals have rendered an increasing interest in the past decade, especially in the telecommunications field. However, very little has been published on the use of these methods in vibration applications. In this paper we show there is strong statistical evidence of cyclostationary behavior in vibrations on an operating boring bar. Methods for estimating the cyclic autocorrelation function and cyclic spectrum for sampled data are developed and results are compared. Some preliminary results from implementing these methods on operating boring bar vibrations are also presented.