A preliminary study has shown that the addition of 15% (v/v) coconut water (CW) to the culture medium significantly improved callus growth, shoot-regenerative capacity, and shoot growth in leaf disk cultures of spinach (Spinacia oleracea L.). Subsequently, the influence of a range of CW concentrations, 0%, 5%, 10%, 15%, or 20% (v/v), was examined. Callus weight obtained after 5 weeks showed direct relationship to the concentration of CW. This stimulator action was observed in both cultivars tested in this study, `High Pack' and `Baker'. On CW-containing medium, shoot regeneration was expedited to 4 to 5 weeks compared with 8 to 12 weeks on a CW-free medium. Callus of `Baker' induced on a CW-free medium exhibited a significant increase in shoot regeneration frequency when transferred to a regeneration medium enriched with CW, suggesting that the addition of CW to the regeneration medium only is sufficient to achieve improved regeneration.