In the competitive world of efficient beer production, high utilization of raw materials and equipment together with smooth operation are advantages, when the quality of beer is not sacrificed. High gravity brewing has proved to be a technique that helps in these aims. There are more and more research papers about very high gravity brewing, original gravity exceeding 18 degrees Plato. Continuous fermentation with immobilized yeast has already a few industrial scale applications. Potentially this technique can improve the productivity of fermentation many fold. In this paper we present data from laboratory scale main fermentations using original gravities between 15 and 24 degrees Plato and immobilized yeast. The yeast strain used was a production strain from a Finnish brewery. Porous glass beads were used as the carrier. Aroma compounds were analyzed by gas chromatography. Yeast viability was analyzed by methylene violet staining. The worts were prepared from malt extract (Oy Lahden Polttimo Ab, Finland) and lower original gravities were obtained by diluting the 24 degrees Plato wort with brewing liquor. The optimal gravity found in regard to ethanol productivity was between 18 and 21 degrees Plato. The highest ethanol concentration in the beers exceeded 11 vol/vol per cent. The degree of apparent attenuation was 81 per cent, 77 per cent, 51 per cent and 38 cent with 15 degrees Plato, 18 degrees Plato, 21 degrees Plato and 24 degrees Plato, respectively, at 10 degrees Centigrade and with residence time of two days. With 24 degrees Plato wort 74 per cent was reached when residence time was raised to 4 days and temperature was increased to 20 degrees Centigrade. At 10 degrees Centigrade the viability of yeast in the outflowing beer was highest with original gravity of 24 degrees Plato and lowest with original gravity of 15 degrees Plato. The aroma compound profiles of the beers produced were quite similar, except for acetaldehyde. The results show that very high gravity brewing using immobilized yeast is possible. The beers produced had similar aroma compound profiles. The ethanol toxicity may have a lower influence in fermentations using immobilized yeast than in batch fermentations. On the other hand, the laboratory scale fermentations using immobilized yeast may be an effective tool in screening for ethanol tolerant strains or in finding out process parameters to facilitate very high gravity brewing.