Studies of the swan mussel population in lake Dąbie (Odra estuary) were conducted in 2007. Measurements were taken of shell length, height and girth, and age was determined. The Anodonta cygnea individuals studied were from the 1+ to 5+ age classes. Clear differentiation was noted in the meristic characters of the mussels collected from the northern part of the lake (Dąbie Wielkie) and from the southern part (Dąbie Małe). The percentage share of individuals in the age structure was also different; however, individuals from the 2+ and 3+ age classes dominated in both parts of the basin. The share of the oldest individuals (4+ and 5+ age classes) was small in Dąbie Wielkie. Mean±SE mussel length of examined population from Dąbie Wielkie amounted to 65.6±0.04 mm, height 36.5±0.66 mm, and girth 21.2±0.43 mm. Means for meristic characters of shells A. cygnea from Dąbie Małe lake were length 65.6±1.06 mm, height 40.0±0.75 mm and girth 22.2±0.36 mm. The dependency among the meristic characters of shell length, height, and girth of the A. cygnea individuals studied exhibited a high, positive correlation. The correlation between the studied meristic characters and the age of the swan mussels did not exhibit a strong dependence.