An online inquiry service (OIS) is an innovative service designed to make medical re-sources more accessible, especially in remote areas. An OIS provides patients with an alteative method of consulting a physician. This study develops a game-theoretical queueing model to examine the impact of OISs on gatekeeping systems. In such sys-tems, patients are heterogeneous in terms of their travel costs. Here, we compare the performance of gatekeeping systems with and without an OIS. As such, we show that, owing to physicians’ reduced diagnostic ability when working online, an OIS reduces pa-tients’travel costs, increases the flow of patients to specialists, increases the total waiting time in the system, and decreases the total health surplus of patients. Moreover, we demonstrate that when patients are not sensitive to delays, introducing an OIS always reduces their total cost. These findings are consistent with the intuition that patients are better off when more options are available. Interestingly, when patients are sensitive to delays, introducing an OIS may increase their total cost. This paradoxical result occurs when patients’sensitivity to delays is high, because those who consult a physician online impose negative extealities on the system by increasing the waiting cost in both the online and offline channels (which is proportional to patients’delay sensitivity). Finally, we numerically illustrate that the benefit of introducing an OIS is non-monotonic in the system parameters; thus, caution is required when designing policies to regulate OISs.