The aim of the study was to investigate the association between working memory capacity and golf performance in a dual-task paradigm. Twenty-eight golfers with ages varying from 19-58 participated in the study. The participants were instructed to, after assessing their working memory capacity with digit span tests, hit ten golf putts from varying distances in two different conditions, one single-task condition (just performing the golf putts) and one dual-task condition (golf putts plus a working memory task). In the dual-task condition the participants were given an address (including street name, postal code and city) to remember while hitting all ten putts. After hitting the putts in each condition the participants reported their perceived mental effort. Results from the study showed that participants with higher working memory capacity performed better than participants with lower working memory capacity in general, but especially in the distracted condition. Results also showed that participants with higher working memory capacity perceived less mental effort compared to participants with lower working memory capacity, especially in the distracted condition. The findings from this study indicate that working memory capacity is related to performance and mental effort exerted during performance, especially in a distracted condition.