Isolation from diseased roots of pea plants collected from three locations at El Beheira governorate indicated that, the most frequently isolated fungi are Fusarium solani and F. oxysporum with the averages of 24.07% for both followed by Alternaria solani and Rhizoctonia solani with 14.81% and F. moniliforme with 9.26%, respectively. The disease severity of downy mildew, caused by Peronspora viciae was recorded during 2007/2008 and 2008/2009 at Etay Elbaroud, Badr and Kom Hamada provinces and the averages were 28.37, 22.24 and 13.27%, respectively. The essential oils of Cumin, Caraway and Anise showed the most reducing effect for the mycelial growth of F. solani, F. moniliforme and Sclerotium rolfsii in vitro with the averages of 70.99, 21.92 and 14.96%, respectively. The highest significant reduction of the spores number of F. solani and F. moniliforme was observed with the essential oils of Cuminum cyminum, Carum carvi and Foenculum vulgare. In addition essential oils of C. cyminum and C. carvi reduced the number of sclerotia of S. rolfsii.                                    
      Intercropping of pea with medicinal plants was studied in field trials through two successive seasons. Cropping pattern side/side combination showed certain reduction of pea damping-off disease and disease severity of downy mildew than sole pea (check). Total damping-off was reduced using intercropping with C. carvi, F. vulgare and Pimpinella anisum compared with sole pea with averages of 39.19, 48.00 and 48.29% during 2007/2008 and 33.46, 39.33 and 40.33% during 2008/2009, respectively. Intercropping pea with medicinal plants F. vulgare, C. carvi, Anethum graveolens and P. anisum were more effective in decreasing disease severity of downy mildew with the averages of 20.20, 20.58, 21.27 and 22.83% during 2007/2008, respectively compared with check (sole pea).                                                                                                           
       Pea intercropped with some medicinal plants could regulate soil microbial community such as actinomyces, bacteria and fungi effectively. The results showed that soil rizosphere was improved, and the fungal diversity differed.  Fusarium spp. and R. solani were found only when pea intercropped with Cuminum cyminum and Nigella sativa. No familiar pathogens were found with intercropping with C. carvi, F. vulgare and P. anisum. The CFU of bacteria in case of intercropping with C. carvi and N. sativa was the highest during the two growth stages of pea, and that of actinomycets in all six intercropping treatments was increased during the flowering stage of pea. The use of intercropping system in pea with medicinal plants as a mean for natural disease control is discussed.                                                                                                                              
         Intercropping pea with C. carvi increased pea fresh and dry weight in addition to the weight of 100 seeds for both seasons (2007/2008 and 2008/2009) more than other intercropping treatments and sole pea. In contrast, the intercropping with C. cyminum and N. sativa had the least values.