The purpose of this article is to report the experience of the Department of Hospital Pharmacy of a mid-size hospital during the peak of the COVID-19 pandemic. The human and material resources available in a mid-size hospital were more limited than in larger hospitals of the region. In this article, we describe how this Department of Hospital Pharmacy was reorganized to meet the increase in activity, the strategies developed and the lessons learned for future pandemics. The COVID-19 pandemic had a higher impact in Leganes, a city in the south of Madrid, with a population of 190,000. In the face of the dramatic increase in the proportion of patients attending our hospital between March and April 2020, the Severo Ochoa University Hospital increased the number of beds by 24.5% and fitted out new premises inside and outside the hospital (sports centers). The mean number of patients seen in our Emergency Department every day passed from 70-80 to a peak of 286 patients, with 652 hospitalized patients. The situation of emergency created by this infectious disease, with management protocols changing constantly, had a dramatic impact on the activity of hospital pharmacies. Thus, the pandemic has affected areas of economic management, magistral preparation, dispensing of medication to inpatients, ambulatory patients, patients monitored at home, institutionalized patients, and patients from private hospitals and field hospitals. Other areas affected include training, clinical trials, pharmacovigilance, and counseling boards. Two strategies were adopted to overcome these problems: a strategy centered on human resources (staff reinforcement, reallocation of responsibilities), and a strategy centered on processes (some processes were reinforced to meet the increase in activity, whereas other were temporarily suspended or reduced to the minimum).Conclusions: The Department of Hospital Pharmacy plays a key role in hospitals and has been significantly reinforced to meet the dramatic impact of the pandemic on this service. This Department has been able to reorganize its processes and take over new responsibilities such as telepharmacy and home dispensing. Hospital pharmacies play a crucial role in pharmacotherapeutic decisions in hospitals. As in other Departments, training is the area more significantly affected by the pandemic.