Suicide rates in the 3 southernmost provinces in Argentina were analyzed; suicide rates were 5.9 (in women) & 21.4 (in men) per 100000 compared to national rates of 3.1 (in women) & 15.5 (in men). Explanatory factors may include race, socio-economic differences, temperature, & diurnal or seasonal light variation. The extreme seasonal variation of light & dark at high latitudes may be linked to high suicide rates & seasonal affective disorders & suggests the possibility of preventive light therapy. (LC) (4 refs)