The effects of sand solution calcium (Ca) concentration and pH on the growth of narrow-leafed lupin (Lupinus angustifolius L.) were examined in an attempt to assess the relative importance of these two soil factors. Two pH (6.5, 8.5) and three Ca concentration treatments (0.625, 6.25, 16.25 mM) were applied by growing lupin in columns of sand which were flushed regularly with otherwise complete nutrient solutions. Root and shoot weights 63 days after sowing were reduced by both increasing pH and increasing Ca concentration. The pH x Ca interaction effect on shoot weight suggested increasing Ca played an important role (which was greatest at pH 6.5) in reducing lupin growth. It was unlikely that growth was reduced by either disrupted iron (Fe) nutrition or poor nodulation of the lupins.