Two field experiments were conducted at the Experimental Farm, Faculty of Agriculture, Mansoura University during 1994/95 and 1995/ 96 winter growing seasons, to study the effect of different patterns of intercropping faba bean (Vicia faba, L.) and onion (Allium cepa, L.). as well as mineral and bio-phosphatic fertilization on growth and yield of both crops. A split-split plot design with four replications was used. The main plots were occupied with intercropping systems and pure stand of faba bean and onion, as follows: faba bean on one side of the ridge with onion on the other side (1:1), faba bean on both sides of the the ridge and onion on both sides of the next ridge (2:2) and planting onion on raised beds (wide ridges, 120 cm wide) in a four middle rows spaced 20 cm apart and faba bean in two border rows (2:4). The sub plots were devoted to four P205 levels, i.e., control (without phosphorus fertiliza‌tion), 15, 30 and 45 kg P205/fad. The sub sub plots were assigned to phosphate Bio-fertilizer (Phosphorin) application, i.e. with and without the addition of phospharin. The results showed that faba bean plant height, number of bra‌nches/plant and seed yield/fad were higher in solid planting. The inter-cropping system of 2 rows of faba bean : 4 rows of onion resulted in maximum values of number of pods/plant, number of seeds/pod, seed yield/plant and 100-seed weight, compared with other intercropping systems. Raising P205 to 45 kg/fad increased faba bean plant height, number of branches/plant, number of pods/plant, number of seeds/pod, seed yield/plant, 100-seed weight, seed/fad and seed protein percent‌age. Application of biophosphatic fertilizer (Phosphorin) resulted in an in‌crease in plant height, number of branches and pools/plant, number of seeds/pod, seed yield/plant, 100-seed pod, seed yield/plant, 100-seed weight, seed yieId/fad as well as seed protein content. With respect to onion, solid stand was associated with the maxi‌mum number of leaves/plant, fresh and dry weight/plant, bubing ratio, marketable yield/fad, average bulb marketable yield/fad, average bulb weight and total soluble solids (TSS), followed by the intercropping system of 2 faba bean: 4 onion. The earlier maturity and lower culls yield/fad resulted from solid planting of onion. Higher P-level (45 kg P205/fad) resulted in marked increase in plant height, number of leaves/plant, fresh and dry weight /plant as well as bulbing ratio and earlier maturity. Adding 30 kg P205/fad increased av‌erage bulb weight, culls yield/fad, marketable yield/fad.Application of bio-phosphatic fertilizer (Phosphorin) markeadly increased fresh and dry weights/plant, marketable yield, average bulb weight, TSS and dry mat‌ter content in onion bulbs.