Background: General Practitioners have limited means to compete. As quality is hard to observe by patients, GPs have incentives to signal quality by using instruments patients perceive as quality. Objectives: We investigate whether GPs exhibit different prescribing behavior (volume and value of prescriptions) when confronted with more competition. As there is no monetary benefit in doing so, this type of (perceived) quality competition originates from GPs satisfying patients' expectations. Method: We look at market level data on per capita and per contact number of items prescribed by GPs and the value of prescriptions for the Belgian market of General Practitioners. We test to which extent different types of variables explain the observed variation. We consider patient characteristics, GP characteristics, number and type of GP contacts and the level of competition. The level of competition is measured by GP density, after controlling for the number of GPs and a HHI. Results: We find that a higher number of GPs per capita results in a higher number of units prescribed by GPs, both per capita and per contact. We argue that this is consistent with quality competition in the GP market. Our findings reject alternative explanations of GP scarcity, availability effect in GP care consumption and GP dispersing prescription in time due to competition.