An accurate algorithm for screening for chlamydial infections is available in general practice, but GPs experience numerous barriers to sexually transmitted infections (STI) counselling. In this study we assessed if a short educational package, under the form of a commented video footage on communication skills, was helpful in implementing the screening strategy. A cluster randomised controlled trial was carried out in 36 general practitioners in Antwerp, Belgium. Main outcome measures were: number of patients included in the risk assessment, number of patients tested, and proportion of appropriately tested patients. The results show that GPs in the intervention group did not include more patients overall, but that the quality of the screening process was significantly better (81.6% versus 56.2% appropriate tests, P = 0.02). Conclusively, GPs who participated in a short educational package on communication skills, selected eligible candidates for screening more accurately and decreased the risk of overscreening.