ABSTRACT Introduction According to a substantial body of research, electrolyte abnormalities are a common manifestation in coronavirus disease 2019 (COVID-19) patients and are associated with adverse outcomes. This study aimed to investigate electrolyte imbalances in COVID-19 patients and assess their relation to mortality. Methods Adult COVID-19 patients hospitalized in the Security Forces Hospital in Saudi Arabia from June 8th till August 18th, 2020 were enrolled in this retrospective observational study. We examined baseline characteristics, comorbidities, acute organ injuries, medications, and electrolyte levels including sodium, potassium, chloride, calcium, bicarbonate, phosphate, and magnesium on ICU admission, as well as every following day of ICU stay, until death or discharge. Patients were stratified according to survival, and differences in variables between groups were compared using Mann-Whitney’s U test or Fisher’s exact test. Longitudinal electrolyte profiles were modeled using random intercept linear regression models. Results A total of 60 COVID-19 patients were enrolled. Compared to survivors, non-survivors had significantly higher sodium and phosphate on admission and death, higher potassium and magnesium at death, and significantly lower calcium at death. Abnormalities in admission levels of chloride and bicarbonate were also more frequently observed in non-survivors. Furthermore, in the deceased group, we observed a daily increase in potassium and phosphate levels, and a daily decrease in sodium and chloride. Finally, calcium increased in non-survivors over time, however, not as significantly as in the survivor group. Conclusion Admission levels of electrolytes and changes over the course of ICU stay appear to be associated with mortality in COVID-19 patients.