We measured parameters of calcium homeostasis and vitamin D status in HbSS patients (median age 8 years, range 3-19; 8 females, 10 males) and matched HbAA controls living in the tropical island of Curaçao. Serum calcium concentration in HbSS patients [2.32(0.07)mmol/L] was lower (ANCOVA, P = 0.002) than that of HbAA controls [2.44(0.14)]. None of the subjects had hypocalcaemia. There were no differences in serum concentrations of phosphate, total protein, albumin, intact parathyroid hormone (PTH), 25-hydroxyvitamin D [87(27) nmol/L in patients, 86(15) nmol/L in controls) and 1,25-dihydroxyvitamin D. There were no significant relations between PTH and 25(OH)D. We conclude that vitamin D status of HbSS patients in Curaçao is adequate.