The aim of this study is to compare the adherence to the guidelines in patients presenting with hyponatremia defined as a sodium (Na) level ⩽120 mEq/L, treated with 3% hypertonic saline or normal saline. The comparison included 3% hypertonic saline use, safe serum sodium increases within 24 and 48 h, frequency of hyponatremia-related complications, and length of stay. This retrospective observational study enrolled 122 patients with serum sodium ⩽120 mEq/L admitted to the Internal Medicine Department, King Abdulaziz Medical City, National Guard-Health Affairs (NGHA), Riyadh, Saudi Arabia, from January 2016 to December 2017. The patients were treated with either 3% hypertonic saline or normal saline. Of the 122 patients, 105 (83.3%) received normal saline, and 17 (13.5%) received hypertonic saline. In the normal saline group, the mean serum sodium increase at 24 h was lower (6.60 ± 4.75) compared to the hypertonic saline group (9.24 ± 5.04). The length of stay was longer in the normal saline group (10.35 ± 13.90) compared to the hypertonic saline group (4.35 ± 3.39). A small proportion (8.7%) of the normal saline group had a serum sodium increase >12 mg/dL at 24 h compared to 29.4% for the hypertonic saline group, and the difference was statistically significant (p value = 0.013). Almost one-third of the sample (36%) presented with complications, the majority (77.3%, n = 34) had a serum sodium of ⩽115 mg/dL, and 22.7% (n = 10) with a serum sodium of 116-120 mg/dL (p value = 0.041). Despite the strong recommendation for 3% hypertonic saline use in severe hyponatremia, many practitioners still use normal saline, even in patients with serum sodium ⩽120 mEq/L. Normal saline showed some efficacy in managing hyponatremia in asymptomatic cases; however, severe cases may have a delayed correction, hyponatremia-related complications, and an extended length of stay.