Spermatozoal behavior in the reproductive tract of the hen is extremely characteristic as compared with that in the reproductive tract of the mammalian female. Yet there is little information available on the spermatozoal behaviour. This paper presents data concerning the fertility and the finding of spermatozoa in the oviduct of the hen after insemination.1. The longest and the mean times intervening between insemination and the laying of the last fertile egg were 21 and 11.1 days, respectively. Above 90 per cent of the eggs laid until the 6th day following insemination were fertile. Thereafter, there was a tendency toward a gradual decline. The fertilities on and after the 13th day following insemination were shown below 40 per cent.2. Spermatozoa were found in the smear collected from the each part of the oviduct until the 4th day following insemination. Thereafter, the positive findings were limited both in the lower region of infundibulum and the utero-vaginal junction. On the 7th day following insemination, spermatozoa were found in the smear collected from the former. In the smear collected from the latter, they were found on the 22nd day yet.3. The results of histological study were shown that spermatozoa were contained slightly in the glandular cavity of the lower region of infundibulum until the 15th day following insemination and considerably in that of the utero-vaginal junction until the 30th day following insemination.4. Fertility was high for the 1st week following insemination with more than 150 million spermatozoa, but it decreased rapidly when spermatozoa were decreased to 30 million. No fertile egg was obtained by insemination of 4 million. However, in the histological examination, some spermatozoa were found only in the glandular cavity of the utero-vaginal junction.5. In the glandular cavity of the utero-vaginal junction, spermatozoa were found in spite of the fertile or unfetile durations. But in the glandular cavity of the infundibulum, the frequency of sperm finding was high in the fertile duration and was low in the infertile duration.6. When the dead spermatozoa were inseminated, they were unable to enter the glandular cavities of both the infundibulum and the utero-vaginal junction.