BACKGROUND: Early studies have reported various electrolyte abnormalities at admission in patients who progress to the severe form of coronavirus disease 2019 (COVID-19). As electrolyte imbalance may not only impact patient care, but provide insight into the pathophysiology of COVID-19, we aimed to analyse all early data reported on electrolytes in COVID-19 patients with and without severe form. METHODS: An electronic search of Medline (PubMed interface), Scopus and Web of Science was performed for articles comparing electrolytes (sodium, potassium, chloride and calcium) between COVID-19 patients with and without severe disease. A pooled analysis was performed to estimate the weighted mean difference (WMD) with 95% confidence interval. RESULTS: Five studies with a total sample size of 1415 COVID-19 patients. Sodium was significantly lower in patients with severe COVID-19 (WMD: -0.91 mmol/L [95% CI: -1.33 to -0.50 mmol/L]). Similarly, potassium was also significantly lower in COVID-19 patients with severe disease (WMD: -0.12 mmol/L [95% CI: -0.18 to -0.07 mmol/L], I(2)=33%). For chloride, no statistical differences were observed between patients with severe and non-severe COVID-19 (WMD: 0.30 mmol/L [95% CI: -0.41 to 1.01 mmol/L]). For calcium, a statistically significant lower concentration was noted in patients with severe COVID-19 (WMD: -0.20 mmol/L [95% CI: -0.25 to -0.20 mmol/L]). CONCLUSIONS: This pooled analysis confirms that COVID-19 severity is associated with lower serum concentrations of sodium, potassium and calcium. We recommend electrolytes be measured at initial presentation and serially monitored during hospitalization in order to establish timely and appropriate corrective actions.