Recent guidelines regard three-dimensional echocardiography (DE) derived measurements of left ventricular (LV) volumes and ejection fraction (EF) as the method of choice. The feasibility of 3DE and agreement between 2DE and 3DE was examined. Our hypothesis was that a number of patients can only be examined with 2DE in a patient population admitted to a general hospital. Hospitalised patients referred for echocardiography by residents on call who found grounds to perform a pocket-sized ultrasound examination (PCU) were included. A subsequent 2DE and 3DE was planned. 3DE was considered unfeasible in the presence of irregular heart rhythm and poor quality imaging (included inability to hold breath). Agreement was evaluated with correlation and Bland-Altman analyses. Of 273 consecutive patients examined with 2DE, 202 (74 %) had satisfactory 3DE images for LV volume and EF measurements. Reasons for exclusion of 71 patients from the 3DE study included irregular heart rhythm in 58 patients and poor quality images in 13 patients. Median LV end-diastolic volume was 146 mL with 3DE and 161 mL with 2DE (p < 0.001). The respective values for LV end-systolic volume were 76 mL and 83 mL (p < 0.001), and for LVEF 48 % and 49 % (p = 0.061). Optimal 3DE assessment of LV volumes and EF could only be performed in 3/4 of patients. A significant overestimation of LV volumes was observed in terms of 2DE versus 3DE, whereas no such difference was found for LVEF.