To examine the relation of "shall-issue" laws, in which permits must be issued if requisite criteria are met; "may-issue" laws, which give law enforcement officials wide discretion over whether to issue concealed firearm carry permits or not; and homicide rates.We compared homicide rates in shall-issue and may-issue states and total, firearm, nonfirearm, handgun, and long-gun homicide rates in all 50 states during the 25-year period of 1991 to 2015. We included year and state fixed effects and numerous state-level factors in the analysis.Shall-issue laws were significantly associated with 6.5% higher total homicide rates, 8.6% higher firearm homicide rates, and 10.6% higher handgun homicide rates, but were not significantly associated with long-gun or nonfirearm homicide.Shall-issue laws are associated with significantly higher rates of total, firearm-related, and handgun-related homicide.