Dendrocalamus hamiltonii and Schizostachyum dullooa are the two important threatened bamboo species of Bangladesh. They flowered gregariously during 1996 to 1998 and 1999 at the bambusetum of Bangladesh Forest Research Institute,Chittagong and RangapaniTeaEstate, Hazarikhil, Chittagong respectively. The flowering cyclesfor D. hamiltonii were estimated as 43 + 5 years and for S. dullooa as 45 + 2, 35 + 2 and 15 + 2 years. Observations were made on flowering nature, death and seed characters of these species. The germination and seedling characters were also recorded. Planta tions of both the species were raised with seedlings by the Forest Department and the NGOs. In future these will be used as ex situ conservation plots.