Plasma levels of procollagen type 1 N-propeptide (P1NP) and C-terminal telopeptide of type 1 collagen (CTX) are bone turnover markers (BTM) used to predict risk of fracture. We compared the effects of vitamin D supplements on plasma levels of P1NP and CTX in the Biochemical Efficacy and Safety Trial of vitamin D (BEST-D) trial (305 participants) after treatment with 2000 IU/d or 4000 IU/d vitamin D3 or placebo. The results of BEST-D were combined in a meta-analysis of all trials of vitamin D v. placebo on levels of P1NP (12 trials, 2654 participants) or CTX (16 trials, 2695 participants). In BEST-D, allocation to vitamin D3 resulted in a dose-dependent increase in 25-hydroxy-vitamin D (25(OH)D) levels but had no effects on P1NP or CTX. Geometric mean (se) levels at 12 months were similar for P1NP (41·7 (0·7) v. 42·9 (1·0) ng/ml; P = 0·29: either dose v. placebo) and likewise for CTX (0·23 (0·01) v. 0·23 (0·01) ng/ml; P = 0·98). In a meta-analysis of eighteen trials, the average difference between the within-trial change in P1NP for allocated vitamin D and control was −3·3 % (95 % CI −5·6, −1·0, P < 0·005). For CTX, this difference was slightly greater (−3·8 % (−6·8, −0·8); P = 0·01). There was no significant heterogeneity between these trials after stratifying trials with or without Ca, higher or lower doses of vitamin D, or lower v. higher pre-treatment levels of 25(OH)D. Overall, vitamin D supplementation was associated with modest reductions in both P1NP and CTX, and results provide support for further trials of vitamin D for prevention of fracture in older people.