The dominant RN(-) allele occuring in the Hampshire pig breed is associated with a high glycogen content in glycolytic muscles. To determine the RN phenotype in meat, certain alternative rapid methods were studied. Instead of using whole muscle, meat juice released from post-mortem longissimus dorsi muscle was used in the analyses. Carriers of the RN(-) allele were distinguished from non-carriers on the basis of the concentration of glucose + glucose-6-phosphate (spectrophotometrically determined), glucose only (determined with a rapid assay for blood glucose in diabetic patients) or the osmolality of meat juice. These results were compared with a classification based on the glycolytic potential or the residual glycogen (sum of [glycogen], [glucose] and [glucose-6-phosphate]) in muscle. Higher levels of glucose, of the sum of glucose and glucose-6-phosphate, and of osmolality were found in meat juice from animals of the RN phenotype. The sum of glucose and glucose-6-phosphate in meat juice seems to be a reliable marker for the determination of the RN phenotype in meat. Glucose or the osmolality of meat juice can also be used, but more as a preliminary method.