The morphology of root systems of 14 day-old seedlings of six legume species grown in root boxes was quantified through fractal methods. Kidney bean and groundnut developed root systems with higher fractal dimension (D) than blackgram, cowpea, pigeonpea and soybean. These suggest that the seedlings of kidney bean and groundnut tend to construct a root system more intricately distributed structure as compared with blackgram, cowpea and pigeonpea. The tested legume species could be categorized into three groups based on the root system size (meristem number and root length), D and topology. The D was estimated with two different methods; i.e. box-counting method and mass-radius method. The D determined with mass-radius method (Dmass)was less closely correlated with system size parameters than the D with box-counting method (Dbox), although both Ds are closely correlated with topology, suggesting that Dmass is less sensitive to the parameters relating to system size as compared with Dbox. The Dmass would be a suitable index alternative to Dbox, when we evaluate root systems focusing on branching pattern rather than system size parameters.