The effectiveness of increasing levels of valproic acid on cocaine abstinence was evaluated in an open-label trial of 55 subjects. Significantly lower percentages of individuals with valproate serum levels above 50 mcg/ml reported cocaine use and had less positive urinalyses as compared to those with serum levels less than 50 mcg/ml. The total number of days of cocaine use decreased significantly (p < 0.001) and improved levels of subject functioning were found with increasing serum levels of valproic acid. This pilot study offers confirmation that the divalproex sodium form of valproic acid, when used in sufficient serum levels, may provide an effective pharmacologic adjunct in the management and treatment of cocaine dependency. Copyright © 2001 John Wiley & Sons, Ltd.