Some boron deposits in Turkey contain considerable amounts of arsenic. Arsenic in the boron deposits can create a great risk due to its environmental effects on surface and underground waters. Water sources containing more than a certain concentration of boron and arsenic have negative effects on plants, animals and human beings. Thus, their removals are necessary. In this paper, the removal of arsenic (As) and boron (B) from aqueous solutions by electrocoagulation using aluminum (Al) electrode material was investigated. Specifically, the effects of initial pH, initial arsenic and boron concentrations and operating time on the performance of EC were investigated. Experiments were carried out with different pHs ranging from 2 to 8. Results showed that initial pH was highly effective on the efficiency and high removal efficiencies were observed at initial pH of 4.0 for both arsenic and boron. Initial arsenic and boron concentration affected the removal efficiencies. Arsenic removal efficiency decreased with increasing boron concentration, and boron removal efficiency decreased with increasing arsenic concentration. The results also showed that boron ions prevented to arsenic removal and boron ions competed with arsenic ions. This situation led to the low arsenic and boron removal.