Just east of the Main Gate is Dr. John McLoughlin's House & Apothecary. Between the years 1803 and 1821, three doctors were posted Fort William. All of them had the dual function of surgeon and clerk - that is, they were doctors during the Rendezvous and fur traders for the rest of the year. The large apothecary area doubled as a hospital until a separate hospital was built sometime after 1811.

Medical practice in the fur trade era promoted a certain kind of therapy for treating illness.  The approach can best be summed up in the phrase: "bleed and purge for everything".  In addition to this approach, the doctor incorporated surgical methods for repairing injuries, and newer therapies such as the application of electrical shock. 

Many of the medicines used during this period are still in use, although others would be looked at as being totally useless or even harmful by today's standards.  The large quantities of medicines on inventory in the Apothecary are probably due to the fact that the doctor was sending medicines into the interior with departing fur brigades as a sort of "first aid kit".  These medicines were used to treat a variety of illnesses, from minor digestive problems to life-threatening diseases.

When it came to surgery the doctor at Fort William was as well-equipped as any doctor in the Canadas.  Historically, "surgery" was any medical intervention that was practised directly on the body. Although quite rarely needed, the doctor was prepared to amputate limbs or digits if necessary.  The amputation of limbs during the fur trade period required a great deal of speed because anaesthetic, as we know it, was not in use, and blood loss could not be replaced with transfusions.