Semen were collected from 9 male dogs and frozen by liquid nitrogengas. Frozen semen were thawed at 7$0^{circ}C$ for 8 seconds. About $2{ imss}10^8$ sperm per insemination were inseminated to 10 bitches (3 Retrievers, 4 Chihuahuas, 1 Yorkshire Terriers, 1 Maltese, and 1 Poodle) at three and six days after the estimated peak of luteinizing hormone. For small breed dogs, uretero-renoscope (Kahl Storz, Germany, 12.5 Fr) was used for trans-cervical insemination, whereas cystoscope(Kahl Storz, Germany, 22Fr) was used for large breeds (Retrievers). Pregnancy was diagnosed by ultrasonography at 30 days after insemination. All of 3 Retrievers (100.0%) and 3 bitches of 7 small breed dogs (42.9%) were conceived (60.0% in total). This result indicated that trans-cervical insemination using endoscope is an effective method for AI with frozen semen not only for large breed dogs such as Retriever but also for small breeds.