BACKGROUND Cali, Colombia, has a high incidence of interpersonal violence deaths. Various alcohol control policies have been implemented to reduce alcohol-related problems. The objective of this study was to determine whether different alcohol control policies were associated with changes in the incidence rate of homicides.   
 METHODS Ecologic study conducted during 2004-08 using a time-series design. Policies were implemented with variations in hours of restriction of sales and consumption of alcohol. Most restrictive policies prohibited alcohol between 2 a.m. and 10 a.m. for 446 non-consecutive days. Moderately restrictive policies prohibited alcohol between 3 a.m. and 10 a.m. for 1277 non-consecutive days. Lax policies prohibited alcohol between 4 a.m. and 10 a.m. for 104 non-consecutive days. In conditional autoregressive negative binomial regressions, rates of homicides and unintentional injury deaths (excluding traffic events) were compared between different periods of days when different policies were in effect.   
 RESULTS There was an increased risk of homicides in periods when the moderately restrictive policies were in effect compared with periods when the most restrictive policies were in effect [incidence rate ratio (IRR) 1.15, 90% confidence interval (CI) 1.05-1.26, P = 0.012], and there was an even higher risk of homicides in periods when the lax policies were in effect compared with periods when the most restrictive policies were in effect (IRR 1.42, 90% CI 1.26-1.61, P < 0.001). Less restrictive policies were not associated with increased risk of unintentional injury deaths.   
 CONCLUSION Extended hours of sales and consumption of alcohol were associated with increased risk of homicides. Strong restrictions on alcohol availability could reduce the incidence of interpersonal violence events in communities where homicides are high.
True