Little attention has been paid to understanding the impact of values, attributes and characteristics of drugs workers on therapeutic relationships and treatment outcomes. Interaction of values with other variables is considered to be of importance since values play a role in determining attitudes and behaviours. This exploratory study investigates the impact of drug workers’ personal values on client outcomes within a drug treatment service.Eight drug workers and 58 clients were recruited at a UK charity working with problematic drug users who are also socially excluded. Drug workers completed a validated questionnaire to elicit their personal values. Client outcomes were assessed using the Christo Inventory for Substance Misuse Services. The relationship between client outcomes and worker values were analysed using Spearman's rank test of association.Drug workers prioritising stimulation, self-direction and hedonism value types experienced more positive client outcomes compared with those prioritising security, conformity, benevolence, tradition and universalism types. The value types associated with positive outcomes fall within Schwartz's ‘openness to change’ superordinate dimension, whereas those related to more negative outcomes fall within the ‘conservation’ dimension.The study suggests that drug workers’ personal values may have a significant impact upon client outcomes in the treatment of substance misuse. Reasons for this finding are explored, as are limitations of this study and suggestions for future research.