A two-season sampling program in the Gulf of Kalloni, Greece, documents the foraminiferal fauna of this deep, narrow embayment and demonstrates a close relationship between circulation dynamics and the composition of foraminiferal assemblages. Seventeen stations were sampled in April 1993 and twelve in September 1993. The distribution of foraminiferal assemblages was not compared to selective measures of environmental parameters, as usually done, but to the circulation of tide-and wind-induced currents computed on the basis of a 2D vertical integrated hydrodynamic model. The asymmetric extension of marine influence, resulting from the water circulation, and the greater confinement in the center of gyratory currents clearly affects the distribution of foraminiferal assemblages. Owing to these relationships, six dominant species serve as good descriptors of hydrodynamic conditions; of those, Ammonia tepida and Haynesina sp. are the most important. Q-mode and R-mode cluster analyses, as well as the environment index (Ic) calculated on the basis of selected species, also show clear relationships with hydrodynamics, such as more restricted marine conditions away from the mouth and a stronger marine influence along the southern coast. In particular, Ic appears to serve as a useful tool for a quick characterization of the environment, including the detection of any anthropogenic impact. The most significant impact, high organic matter input, results in a lower density and species richness, a higher Ic index and increased dominance of the tolerant species Ammonia tepida and Haynesina sp.