There is limited information on the influence of Pratylenchus coffeae on the growth and development of coffee plants, in spite of the widespread occurrence of this nematode in coffee plantations. In addition, populations of P. coffeae vary in morphological and molecular features, as well as reproductive fitness and pathological potential. The objective of the present study was to compare the pathogenicity of two Brazilian P. coffeae populations, K5 from Coffea arabica roots and M2 from Aglaonema sp. roots, in terms of their influence on the plant growth and photosynthesis of Arabian coffee (C. arabica). Five experiments were conducted in controlled conditions, and the results demonstrated that K5 is pathogenic on coffee, as it can reproduce and causes obvious damage on the plant. Moreover K5 proved to be very virulent on Arabian coffee, considering its effects on seedling mortality, plant growth and photosynthesis. By contrast, M2 was considered to be of low virulence, or even non-pathogenic, on coffee because it failed to reproduce. Thus, the results indicate that K5 and M2 may be distinct species, supporting the hypothesis of previous authors.