Seeds of Diplotaxis erucoides collected un the fields of the ETSEA of Lleida in spring of 1989 were sown in pots in Mars of 1990 after their conservation at lab temperature and humidity. To estimate the biomass: allocation between different organs during the plant life and to know the reproductive effort at the end of this one, we have regularly determined the dry weight of the following plant parts: a) roots, b) stems and leaves, c) flowers, and d) fruits of 20 plants in each analysis. With the results obtnined we can confirm the following observations: a) a high and positive correlation between the biomass of different parts, b) the biornass destined to reproduction represents a 33% of the total plant biomass, c) there is an increase of the reproductive effort with the size of the plant, d) the correlation caefficient between the number of flowers and the vegetative biomass is better than those observed beetween the reproductive and vegetative biomass, and e) there is a decrease of the vegetative growth and radicular system in the last stages of the plant cycle.