In this study, metazoan parasites of pike (Esox lucius L.) from Lake Uluabat were investigated monthly from January 1993 to January 1994. Parasites belonging to six species were recorded for 133 pike hosts: Argulus foliaceus, Tetraonchus monenteron, Rhipidocotyle fennica, Diplodiscus subclavatus, Raphinascaris acres, and Acanthocephalus anguillae, of which only two specimens of A. foliaceus were found in the gills of one host fish, and a single specimen of A. anguillae and two specimens of D. subclavatus in the intestine of another. Tetraonchus monenteron, R. fennica, and R. acus were the dominant parasite species found in the pike. Tetraonchus monenteron was the most prevalent species found in fish of all sizes during the year of the study. Rhipidocotyle fennica infection rate was highest during summer and autumn and minimal during winter and early spring, with larger pike having more parasites than smaller host pike. The third dominant parasite, R. acres, produced two generations per season, with peaks in spring (April) and autumn (October). There was a negative correlation between size of the host and density of R. acres. Occurrence, density, seasonal changes, and the preferences of the parasite species for various size groups of its pike host are discussed in detail.