Tick samples (Acarina, Ixodidae) were collected for two years on bovidae from the whole Oran area which were brought weekly at the Oran open market (Algeria). The 5,500 ticks thus obtained could be divided into six genera and twelve species. From the phenological analysis the following were defined: three spring species (Rhipicephalus bursa, Rh. turanicus and Rh. sanguineus), three summer species (Hyalomma detritum, H. impeltatum and Boophilus annulatus), three winter species (Ixodes ricinus, Haemaphysalis punctata and Dermacentor marginatus) and three species called perennial (H. marginatum, H. excavatum and H. lusitanicum). In fact, the latter are present on cattle all year around, but in winter, the collected specimens (mostly male and a few females) remain fixed on their host without feeding. The parasitic intensity for each species and its relative distribution pattern were studied monthly on cattle from november 1981 to september 1983. The distribution on host of different species was analyzed. Short rostrum ticks were found to have a significant preference for specific habitats (depending on the thickness of the teguments) while long rostrum species are fixed on more varied sites. In the case of plurispecific infestations of the same area, phenomena of competition-exclusion were not observed. Most of the animals are simultaneously infected by two or four different species of ticks. Taking into account this first estimation, it was possible to define two types of associations both related to the rearing methods and geographical source of bovines.(ABSTRACT TRUNCATED AT 250 WORDS)