The first occurrence of soybean cyst nematode, Heterodera glycines, on beans in Iran was documented when a cyst-forming nematode was detected in a commercial common bean (Phaseolus vulgaris) field in Iran and subsequently identified as H. glycines. The population was identified as HG Type 0. Host suitability of the 11 P. vulgaris cultivars most commonly grown in the country were evaluated with that population in pot and field trials. Pot assays were conducted in a growth chamber and nematode reproduction on the cultivars was compared. In the field trials, host suitability of the tested entries was evaluated in a field naturally infested with H. glycines. In both the pot and field experiments, most of the common bean cultivars were susceptible or moderately susceptible to the HG Type 0 populations of H. glycines. Common bean cvs Sayad and Dehghan were classified as moderately resistant in pot trials and were moderately resistant and moderately susceptible, respectively, in field trials. The occurrence of H. glycines in commercial bean production fields and lack of high levels of resistance of the commonly grown P. vulgaris cultivars could severely affect common bean and soybean production programmes in Iran.