Using a HPLC technique, 54 peaks have been detected in the fruits of yellow pepper; 32 carotenoids (90-94% of the total carotenoid content) have been completely or tentatively identified. The study was carried out quantitatively with fruits in six different stages of maturation. Violaxanthin, antheraxanthin, zeaxanthin, lutein, @-cryptoxanthin, @-carotene, a-cryptoxanthin, cy-carotene, and probably "post-mortem artifacts" (furanoid oxides and cis isomers) were found. @-Cryptoxanthin 5,6-epoxide, a precursor of cryptocapsin present in red pepper, was also identified. But carotenoids with K-, 5,6 dihydro-3,5,6,-trihydroxy-B, and 5,6-dihydro-3,6-epoxy-5-hydroxy-@ (oxabicyclo[2.2.1]) end groups usually found in red pepper were not detected. In the massive biosynthesis of violaxanthin during maturation, the rates of hydroxylation exceeded those of epoxidation.