This paper presents some preliminary results of consecutive 23 months of phenological observations in the tropical rain forest of southern Cameroon. Data have been recorded between September 1996 and July 1998 in the Ebom forest, where 20.6 km of transect have been established, involving 1 320 trees of 86 indigenous timber species within 28 families. The data collected give an appreciable of the probability of species being leafless, in flower or fruit in a certain month.