Technical Abstract: Castor (Ricinus communis L.) is an important oilseed crop with significant industrial value. However, the presence of ricin toxin and hyper-allergenic 2S albumins in seed poses health concern during its cultivation and processing. As part of a genetic approach to eliminate ricin and 2S albumins from castor, we have investigated the expression of ricin and 2S albumin genes during seed development. Northern analyses showed that the ricin mRNA levels increased significantly during the middle and late stages of seed development, whereas 2S albumin mRNA accumulated transiently in the middle stages of seed development. The different temporal patterns between ricin and 2S albumin genes indicate distinc regulatory mechanisms involved in their respective gene expression. We further examined the similarities of castor 2S albumins to those from different plant species, including their phylogenetic relationship, common amino acid domains and possible secondary biological functions.