Electrolytes disturbances are commonly observed in clinical practice. However, magnesium (Mg) disorders are often poorly considered. Our primary aim was to update the prevalence and the incidence of hypomagnesemia and hypermagnesemia in a real-life scenario. The secondary aim was to investigate the association of Mg disturbances with age and gender. Data from patients whose Mg serum levels were measured between January 2015 and December 2017 at our University Hospital were recorded. Hypomagnesemia was defined by Mg levels <1.5 mg/dL and hypermagnesemia by levels> 3.8 mg/dL. Hypo and hypermagnesemia cases were considered according to age, gender, year of observation and setting of subjects including outpatients and inpatients. In particular, inpatients were recruited from a total of 25 Hospital Divisions (i.e. Cardiology, Endocrinology, Geriatrics, Hematology, Intensive Care, Internal Medicine, Infectious Disease, Nephrology, Neonatal Intensive Care, Neurology, Neuropsychiatry, Neuroradiology, Oncology, Pulmonology, Pediatrics, Psychiatry, Rheumatology and Surgical Area that included 8 Units). Over the observation period, we recognized 12,696 patients whose Mg levels were checked. Prevalences of hypomagnesemia and hypermagnesemia were 8.43% (n=1071) and 1.78% (n=226) respectively. Hypomagnesemia was encountered more frequently in female [53.3% (n=560)] rather than in male patients [47.7 % (n=511)] (χ2= 4.03, p<0.045) and was significantly influenced by age: the higher prevalence of hypomagnesemia was found in patients over 65 yr. [59.01% (n=632)], whereas a lower prevalence was detected in the other age groups, specifically in 9.52 % (n=102) of patients aged 0-18 yr. and in 31.46 % (n=337) of patients between 19 and 65 yr. (χ2= 592.64; p<0.0001). Incidence of hypomagnesemia decreased over time with a borderline significance only in subjects over 65 yr. (r=-0.99; p=0.07). Geriatrics, Oncology and Intensive Care Division showed the highest incidences of hypomagnesemia. The hypermagnesemia prevalence was observed higher in outpatients in comparison with inpatients from any other Hospital Division and the hypermagnesemia incidence did not significantly change over time (r=0.96; p=0.16). Mg disorders, mainly hypomagnesemia, are quite common in clinical practice particularly in older hospitalized patients. Among the other electrolytes’ disturbances, Mg disorders, because of life-threatening significances, may be checked and corrected.