In a cold greenhouse the vegetative production of Bromus berteroanus Colla was studied under different actual simulated pluviometric regimes of the dry land areas of the Metropolitan Region, Chile. Three levels of total rainfall were used, corresponding to dry, normal, and rainy years, with each year having early, normal, and late distributions. Rainfall levels for each treatment were applied, according to a real calendar time interval between rainfalls, beginning with the first effective rainfall. Phenological development and vegetative phytomass were registered, including shoots per pot, and dry matter of shoots, leaves and roots. In all the types of years studied, B. berteroanus had a determined development with a marked separation of the phenological phases, the vegetative stage was longer than the reproductive one, and both stages were more extended under the greatest rainfall when the distribution was not considered. The phytomass production was affected by the total quantity as well as the distribution of rainfall. In dry years, the greatest total phytomass occurred under early rainfall distribution (9.2 g DM/pot), on the other hand, in normal or rainy years, the greatest production was obtained under late rainfall distributions, 13.7 and 23.1 g DM/pot, respectively. [ABSTRACT FROM AUTHOR]