The aim of the present study was to assess the effect of the lunar cycle phases, the lunar apogee and perigee, and the geophysical factors (humidity, temperature, and rainfall) on the childhood mortality. We designed a retrospective study by reviewing the clinical charts of the population of patient deceases during the lunar pre-phase (a day before), phase (day of lunar change of phase), and post-phase (a day after), between the years 1991-1996 in a children's hospital. From the 44,982 discharges from the hospital in the interval between 1991 and 1996, 2003 corresponded to mortal cases, and 522 died within the 3 days we considered as representative for each phase. The number of deaths was approximately the same in between phases. The percentage of male deaths was higher during phase days than interphase ones. Male deceases exhibited a statistically significant predominance during lunar first quarter, full moon, and new moon. A discreet increase of mortality was present in the months of March, June, August, September, October, and November, as well as during summer and fall, but these increments were not significant. Minimum and maximum temperatures exhibited no relation to this behavioral pattern for deceases, nor the humidity index. Early lactating infants presented a significant higher mortality