BACKGROUND The Dutch Health Council advises a standard daily vitamin D supplementation of 800 IU (20 mcg) for persons aged ≥ 70 years, with a target 25(OH)D serum concentration of ≥ 50 nmol/l. This recommendation is in line with advice from the Institute of Medicine (IOM) (2011) and the Expert Working Group on vitamin D (2012). A target 25(OH)D serum concentration of ≥ 75 nmol/l is also recommended in the literature. It is unknown whether this advice, initially designed for healthy adults/elderly, will lead to vitamin D sufficiency in the large majority of nursing home residents, taking into account the frailty of this population. METHODS Cross-sectional patient file study. Participants were 71 psychogeriatric nursing home residents (25 males, 46 females) with a mean age of 83 (SD 7) years using cholecalciferol capsules (5600 IU) once a week, or cholecalciferol drops (50,000 IU/ml) 3 drops a week (7500 IU), for at least 3 months. Main outcome measure was serum 25(OH)D level after supplementation. RESULTS Of all participants, 19 used cholecaliferol drops and 52 used cholecaliferol capsules. In total, mean serum 25(OH)D was 77 (SD 30) nmol/L and 55 residents (78%) were vitamin D sufficient. Among capsule users, mean serum 25(OH)D was 90 (SD 22) nmol/L and 49 (94%) were vitamin D sufficient. Among users of drops, mean serum 25(OH)D was 41 (SD 8) nmol/L and 6 (32%) were vitamin D sufficient. CONCLUSION In most of these residents, vitamin D supplementation once a week with cholecalciferol capsules containing 5600 IU (equivalent to 800 IU daily) resulted in vitamin D sufficiency (serum 25(OH)D ≥ 50 nmol/L). When choosing a vitamin D preparation for routine supplementation in nursing home residents it should be noted that major differences may exist in efficacy, even when the various preparations contain the same amount of vitamin D.