Vitamin D status is increasingly recognised as an important aspect of patient management on account of the wide-ranging physiological roles ascribed to the hormone1 and the potential to treat those found with low levels. Established risk factors for hypovitaminosis D include darker skin tone, extreme latitude and winter nadir. We sought to screen all of the children with cerebral palsy (CP) listed in the Calvary Rehabilitation Service database for southern Tasmania at a single time point at the end of winter with the hypothesis that higher Gross Motor Function Classification System (GMFCS)2 level might emerge as a risk factor for hypovitaminosis D. In addition to latitude and season, it was recognised that our patients held the potential for a cluster of other risk factors including reduced outdoor activity, anticonvulsant use and fracture susceptibility. National Ethics Application Form ethics approval was obtained, and 38 of 96 patients identified in the database participated. Diagnosis of CP and GMFCS levels were determined clinically, and other information was gathered by questionnaire. Blood sampling was conducted on the same day in the majority, otherwise within 2 weeks of that day in the remainder. 25-OH vitamin D was measured in all children, and calcium, phosphate, parathyroid hormone and alkaline phosphatase were measured on the separated and saved serum in those whose 25 OH D level was <50 nmol/L. One was ethnic Asian, 37 were Caucasian, 7 were taking anticonvulsants and 4 had spent at least 1 week at lower latitude just prior to sampling. No children were taking vitamin D supplementation, and none were in institutional care. Twenty children were GMFCS I, two were GMFCS II, four were GMFCS III, five were GMFCS IV, and seven were GMFCS V. Ten were less than 4 years old, 18 were between 4 and 12 years old, and 10 were between 12 and 18 years old. The 25 OH D levels according to GMFCS level are shown in Figure 1. Thirteen children (34%) were vitamin D deficient. Twelve of these had mild deficiency, and one child was moderately deficient as defined by the Australasian Paediatric Endocrine Group.3 The mildly deficient patients included 7 of 26 children who were GMFCS I–III, 5 of 12 children who were GMFCS IV–V, 6 of 10 children who were less than 4 years old, 2 of 7 children who were anticonvulsant users and the sole ethnic Asian patient. The only moderately deficient patient was 17 years old, GMFCS level V and an anticonvulsant user. Comparison of mean vitamin D levels in various groups was made by two-tailed unpaired t-testing. Those in the GMFCS I–III group had a higher mean vitamin D level than those in the GMFCS IV–V group; however, the difference was not significant (P = 0.181). Anticonvulsant users (n = 7) had a lower mean vitamin D level than non-anticonvulsant users (n = 31); however, the difference again was not significant (P = 0.287). Patients who had recently travelled to lower latitude (n = 4) had a mean vitamin D level, which was higher than the other 34 patients who had not travelled; however, the difference was not significant (P = 0.0726). Those aged less than 4 years (n = 10) had a significantly higher vitamin D level than the 28 patients aged 4 years or older (P = 0.0492). 25-OH vitamin D level (nmol/L) versus Gross Motor Function Classification System level. Thus our study documents another group of children with a substantial proportion of vitamin D deficiency, as has been seen previously in Victoria.4 Higher GMFCS level did not emerge as a clear independent risk factor for hypovitaminosis D in our study. Patients younger than 4 years with CP appear to be at increased risk of hypovitaminosis D compared with older patients with CP. To date there is no well-designed study that explores the relationship between level of physical disability and vitamin D status using a reliable tool such as the GMFCS in a larger cohort. Such a study would ideally control the confounding variables of seasonal variation, range of latitude and skin tone, as was the case with our study. The authors would like to thank the patients who were involved in the study and their families; Paediatric Ambulatory Care Unit Staff, Royal Hobart Hospital; and Lesley Willis for secretarial support.