Matsuda S (Department of Preventive Medicine and Community Health, School of Medicine, University of Occupational and Environmental Health, Japan, Yahatanishi-ku, Kitakyushu, 807, Japan). Seasonal variation of births in a locality of Hochiminh city, VietnamSeasonal variations of births in a community of Hochiminh city, Vietnam are analyzed by a Kolmogorov-Smirnov type statistics.<BR.The excess in births is observed in the latter part of the year, but there is a difference in the timing of the peak of the first and subsequent births, that is, July to August for the first births and September and November for the subsequent births. This fact suggests that associated factors are different between the two parity groups. It does not seem that marriages and the lunar new-year holidays are important enough to create seasonal variations in conception in this population.On the other hand, the traditional social belief of reproductive activity seems to play some role in creating the seasonality in births. And temperature hypothesis is also plausible for this population.