Immediate serial recall of verbal information is supported by working memory resources. From the perspective of Baddeley’s working memory model a separate working memory component is responsible for the reproduction of words, letters or numbers: the phonological loop (Baddeley, 1986). The phonological loop consists of (a) a phonological store that holds information for about 2 seconds and (b) articulatory processes that maintain information in this store (rehearsal). Subjects are unable to use the rehearsal mechanism of the phonological loop if they have to articulate some word while maintaining information. Consequently, the reduction of memory performance by concurrent articulation (“effect of articulatory suppression”) indicates the functioning of the phonological loop. Recent research has shown that the phonological loop is involved in the retention of nonverbal information: Different lines of evidence suggest that rhythm patterns are maintained by the phonological loop (e.g. Glenberg et al., 1989; Grube, 1996; Saito & Ishio, 1998). The present experimental study was designed to investigate the influences of phonological working memory and knowledge base on immediate reproduction of rhythm patterns. Subjects had to reproduce auditory rhythm patterns of 2 – 3 seconds duration by pressing a button. In a standard condition subjects reproduced the patterns after 2.5 seconds retention interval. In an articulatory suppression condition subjects articulated during the retention interval. The influence of expert knowledge was indicated by the difference between performance of musicians and musical laymen. As a third experimental factor the metric status of the rhythms was manipulated (Povel, 1981). Analyses demonstrate the influences of the phonological loop of working memory and expert knowledge on rhythm memory. Metric rhythms seem to profit especially from phonological memory, and this interaction is more profound for musicians than for musical laymen. The phonological loop seems to be a powerful mechanism in processing metric rhythms.