Chromoplast fractions from mature, chlorophyll-less 'Valencia' orange (Citrus sinensis L. Osbeck) flavedo (= the outer coloured layer of citrus peel) showed considerable chlorophyllase activity. Acetone powders prepared from chromoplast fractions had 2.5× higher specific activity than those prepared from whole flavedo. Exposure of mature, chlorophyll-less fruit to ethylene caused a 2.5 to 4.0 fold increase in chlorophyllase activity. Juice chromoplasts showed negligible chlorophyllase activity. The results suggest that chlorophyllase activity as well as its induction by ethylene are not dependent upon the presence of chlorophyll in the tissue.