The content and relative variations of individual carotenoids during the leaflet development stages (I, II, III, A and P) of six species of Ceratozamia (Cycads) were investigated. There is an unusual, transitory and marked presence of six red stroma keto-carotenoids in the first development stages, while the thylakoidal carotenoids showed a low concentration during the same period. As no official A1cm1% coefficients were available, it was necessary to calculate these for the following stroma carotenoids: semi-beta-carotenone (major component), triphasiaxanthin, ceratoxanthin, ceratozamiaxanthin, kuesteriaxanthin and ceratoxanthone. The stroma keto-carotenoids, which reached the highest content in the first development stage (average of 78% of total carotenoids), were always present in the five species: C. fuscoviridis, C. robusta, C. spinosa, C. kuesteriana and C. hildae, but never in C. mexicana. From stage II, the stroma keto-carotenoids decreased and finally disappeared in the green adult leaflets. The thylakoidal carotenoids showed a minimum at stage III, and then increased to a maximum in the perennial leaflets. Among these, beta-carotene showed an anomalous and characteristic behaviour, being a minor component during leaflet development (from stage I to A). In stage P it was markedly exceeded not only by lutein but also by alpha-carotene, neoxanthin and violaxanthin, and in C. robusta also by lutein-5,6-epoxide. Additionally, the alpha/beta ratio in these species is unusual: it increased from 0.3-0.5 to 1.5-3.0 during leaflet development. Moreover, antheraxanthin amounts are very small, while zeaxanthin was present only in the evergreen leaflets of C. mexicana in small quantities. Lutein-5,6-epoxide represented more than 5% of thylakoidal carotenoids in the leaflets of all the species. A revision of the taxonomic rank of C. fuscoviridis is recommended.