The Family Lymnaeidae is comprised of large aquatic snails that are intermediate hosts of parasitic flukes. In the present study, radular morphology, teeth length, and tooth formula of field-collected lymnaeid snails including Galba truncatula (Müller, 1774), Lymnaea stagnalis (Linnaeus, 1758), Radix auricularia (Linnaeus, 1758), and Radix gedrosiana (Annandale and Prashad, 1919) were investigated. The conical and dextral freshwater snails were collected from their natural habitats in West Azerbaijan province, northwestern Iran, in fall 2010. The snails were rinsed, measured, and taxonomically identified. The radula of all specimens was extracted and stained using Mallory II. Besides the morphological variations, the mean length of radular teeth significantly increased with the body size of the examined lymnaeid snails. Morphometric investigation indicated that the mean length of lateral (L) (427.86 ± 6.9 µm) and marginal (M) (427.82 ± 6.86 µm) radular teeth of Lymnaea stagnalis differed significantly from those of other examined lymnaeid snails. The average number of radular M teeth and L teeth were the highest in R. auricularia and L. stagnalis, respectively. The specimens with smaller body size had the most transverse teeth rows (G. truncatula, 115.6 ± 3.7 µm). It was concluded that radular teeth morphology and morphometry within lymnaeid species could be one of the character sets for classification of lymnaeid snails.