The main objectives of this study were to study the parasitic infestation of Lernaea cyprinacea in 4 cyprinids from the Choghakhor Lagoon, Chaharmahal - Bakhtyari Province, west of Iran. A total of 180 cyprinids including Cyprinus carpio (n=101), Carassius auratus (n=47), Capoeta aculeata (n=10) and Alburnus alburnus (n=22) caught, and were studied for Lernaea cyprinacea infestation. Prevalence (C. carpio 61.4, C. auratus 87.2, C. aculeata 70 and A. alburnus 68.2), intensity of infection (C. carpio range 1 to 5, mean 2.1; C. auratus range 1 to 6, mean 1.9; C. aculeata range 1 to 5, mean 2.4; A. alburnus range 1 to 2, mean 1.1), and abundance (C. carpio 1.3, C. auratus 1.6, C. aculeata 1.7 and A. alburnus 0.8) varied with the fish species. A statistically significant difference was found between infestation by L. cyprinacea and fish species (p=0.01), although no statistically significant difference was found between infestation and weight, length and age of the studied fishes (p>0.05). The prevalence was also significantly different (p=0.0) in studying seasons. Population dynamics of L. cyprinacea on fish hosts was studied. The results show that the preferred site of the parasite was body lateral surfaces followed by caudal, dorsal, pectoral and anal fins (P=0.0).