To exploit future genetic gains in biomass for yield potential, it will be necessary to identify traits enabling breeders to discriminate ‘useful’ and ‘non-useful’ biomass to maximize dry-matter partitioning to reproductive structures. While allocation of carbon to the developing spike determines grain sink strength, concurrent growth of other plant organs - particularly the stem - competes for carbon. Previous results showed that dry-matter (DM) reductions to particular stem internodes can improve assimilate partitioning to growing spikes, improving grain number set and harvest index. Stems and other plant organs are formed by structural (mainly in form of cellulose and lignin) and soluble components (mainly fructans), commonly known as water-soluble carbohydrates (WSC). Differences in partitioning to structural or soluble DM at flowering can have a significant effect on associations between reproductive and support structures, potentially affecting grain number, harvest index and yield. For example, a previous study suggested that WSC do not compromise grain number determination during pre-anthesis but are rather beneficial for floret survival under optimal growing conditions. However, studies investigating associations between WSC and sink traits under optimal growing conditions are scarce. The objective of this study was to investigate phenotypic differences in WSC distribution among plant organs and to investigate the role of WSC in associations between reproductive and structural organs at flowering. A set of 26 elite bread wheat CIMMYT cultivars was sown during two field seasons in NW Mexico under optimal growing conditions. Growth and dry-matter partitioning analyses, WSC concentration (WSCC) determination in different plant organs, yield and yield components were performed in all lines. Results from the field experiments showed highly contrasting phenotypes for WSCC in the different plant organs, such as spikes, stems, stem internodes and leaf-sheaths. Negative associations between stem middle internodes and spikes at flowering became stronger when not considering WSC (i.e. just considering structural dry-matter). Differences in expressions of WSCC did have an effect on associations between traits at vegetative stages and traits at harvest. Although higher dry-matter partitioning to WSC appeared to be associated with higher grain number and higher harvest index, net yield effects need to be studied in the context of breeding for higher WSC under optimal growing conditions.