Fleas were collected from 50 flea-infested dogs, which were brought to some pet clinics in Istanbul from June to October in the years 1999 and 2000. The ages of 4 dogs (females) were ranging between 2.5 and 9 months and the remaining 46 dogs (27 males + 19 females) were one year or over. The breeds of dogs were 4 Cocker, 16 Terrier, 5 Setter, 7 Poodle, 4 Pekingese. 2 Pointer, 1 Golden retriever, İ Tibetan spaniel and 10 crossbreed. The dogs were indoor or indoor/outdoor animals. Fleas were collected from the dogs using an electronic flea comb (Epivetâ„¢ Flea zapper). Thirty-seven (74%) of the 50 flea infested dogs had pure infestations with Ctenocephalides felis felis; 2 (4%) with C. canis; 1 (2%) with Pulex İrritans. Nine (18%) dogs had mixed infestations with C.f.felis and C. canis and 1 (2%) with C.f.felis, C. canis and P. irritans. A total of 574 fleas were collected, of which 544 (94.8%) were f.felis. 28 (4.88%) C. canis and 2 (0.35%) P. irritans. The intensity of infestations (No of fleas/No of infested dogs) was 11.6 for C.f.felis, 2.33 for C. canis. 1 for P. İrritans and 11.5 for all over species. The sex ratio (male:female ratio) of fleas from both sexes of dogs was 1: 1.88 for C.f.felis. 1:3 for C. canis and 1:1.91 for all species. It was considered that indoor conditions might be more suitable for the development of C.f.felis than those of other species.