The cotton wilt incidence caused by Fusarium oxysporum f. vasinfectum separate and mixed with Meloidogyne incognita, was studied on artificial substrates containing different sand percentages. When a susceptible cotton variety was used the highest wilt incidence occurred in the substrates containing 60 and 90 percent sand. The inoculum that caused the highest amount of wilt was the mixture of Nematodes and Fusarium. When a resistant variety was used no differences in wilt incidence were observed that could be attributed to differences in sand percentage of the different substrates. Again the highest wilt incidence was obtained with the inoculum consisting of the mixture of nematodes and Fusarium. The inoculum versus substrate interection showed that the incidence of wilt caused by the inoculum consisting only of Fusarium was highest in the substrate containing 90% sand. On the other hand the inoculum of Nematodes and Fusarium caused about the same amount of wilt in the different substrates. This shows the importance of the nematodes on the Fusarium inoculum. The interection also showed that the differences in wilt incidence caused by the different inocula was different in the same substrates, with the exception of the substrate containing 30% sand.