In order to evaluate the functions of putative transcriptional regulatory regions of cotton genes, the upstream regulatory sequences (promoters) of two cotton genes, Gh-sp (seed protein) and Gh-rbcS (ribulose-1,5-bisphosphate carboxylase small subunit), were fused with a bb-glucuronidase (GUS) reporter gene and the cauliflower mosaic virus (CaMV) 35S terminator. These two gene constructs were transferred into cotton (Gossypium hirsutum L. cv. Coker 312) by Agrobacterium-mediated transformation. Transgenic plants from the T0 generation were analyzed for expression of the GUS reporter gene in different tissues and developmental stages of cotton. Qualitative and quantitative analyses indicated the GUS gene driven by the Gh-sp promoter were expressed only during seed maturation, beginning approximately 25 d postanthesis. Expression of the GUS reporter gene driven by the Gh-rbcS promoter was detected primarily in leaf tissue from transgenic plants. Levels of GUS expression in leaves of Gh-rbcS/GUS transgenic plants was comparable to that in transgenic cotton plants containing a GUS gene construct controlled by the CaMV 35S promoter. These results indicate that these two tissue-specific promoters have the potential to be used to differentially express interesting genes in developing seeds or leaves of transgenic cotton.