A field experiment was conducted with 10 deep-water rice varieties (nine traditional and one improved), viz. Amona, Maguri, Rangoli, Kakua, Panikakua, Deoribao, Moimonsingia, Duatkalam, Dalbao and PJNB-96-10, to study their physiological performance, grain-quality characters and yield. Among the cultivars, significant variations were recorded in plant height, root length, number of internode, ... [Show full abstract] tiller number, number of ear-bearing tillers, panicle length, panicle weight, number of spikelets per panicle and filled grain percentage. The highest number of spikelets per panicle (199), filled grain percentage (95 %) and grain yield (4.32 t ha−1) were recorded in Maguribao. The highest grain length was recorded in PNJB-96-10 (9.5 mm), whereas highest grain thickness was observed in Duatkalam (2.8 mm). Glutelin was the most dominant fraction of protein in all the tested cultivars. Maguribao showed the highest glutelin content (26.7 mg g−1 dry weight), whereas Panikakua showed the highest amylose (24.45 %) and crude fat (4.64 %) content. Differences were also recorded among cultivars in fibre, ash and iron content in grain. Maguribao was found to have superior physiological traits for growth and hence may be considered for inclusion in deep-water rice breeding programmes.