Abstract: The effects of row spacing on faba bean L. growth was investigated during the two growing seasons 2003-2005 at two locations under Mediterranean rainfed conditions of Jordan. Five row spacing (30, 40, 50, 60 and 70 cm) were used in a Randomized Complete Block Design (RCBD) with four replications. The results showed that higher row spacing (50-70 cm) resulted in the greatest yield with a reduction at the narrow spacing. The increase in the characters studied were: (~50%) for grain, (53-100%) for nodule dry weight, (77%) for nodule number and (34%) for root dry weight. The behavior of faba bean under various spacing with respect to vegetative growth and root growth varied according to the location. This indicates that under different environments the vegetative growth is affected more than root growth. High significant positive correlation was found between vegetative growth and yield (r = 0.60 and 0.63), nodule dry weight (r = 0.44 and 0.67), nodules no/plant (r = 0.42 and 0.75) and root dry weight (r = 0.46 and 0.85). The same was found for the root growth (root dry weight) which was highly correlated with yield (r = 0.38 and 0.89), nodule dry weight (r = 0.86 and 0.80) and nodules no/plant (r = 0.30 and 0.59) at the two locations during the two seasons. This prominent association between vegetative and root growths and nodules traits illustrated the importance of leguminous crops in fixing atmospheric N₂ which is highly demanded by the plant for it`s growth. This study demonstrated good prospects for faba bean improvements under rainfed conditions. Moreover, it revealed the importance of leguminous crops in nitrogen fixation which is entirely reflected on the performance of the crop and on ecology.