The purpose of the present study was to evaluate the association between lithium levels in the public water supply and incidences of homicide in Greece. A total of 149 samples of drinking water were collected from 34 out of 52 prefectures, and data for homicides were taken from National Statistic Service of Greece (Hellenic Statistical Authority - EL.STAT). The average lithium level was 11.10 μg/l (SD = 21.16). The results indicate that there is a tendency for lower mean number of homicides in the prefectures with high levels of lithium in drinking water (R(2) = 0.054, β = -0.38, p = .004). Considering the results of our previous study, which showed an inverse association between the lithium levels in drinking water and the incidence of suicide, homicide, rape, and drug abuse, we suggest that natural lithium level intake may influence impulsiveness, a factor that mediate to the manifestation of both suicidality and aggressiveness.