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The literature on the epidemiology, pathogenesis, and laboratory identification procedures for group B, beta-haemolytic streptococci (Streptococcus agalactiae) is reviewed. Sampling methods for optimum isolation of beta-haemolytic streptococci, particularly group B, were investigated and the role of transport media in maintaining the survival of these bacteria on swabs was assessed. The results indicated that, in general, none of the recognised transport media preparations offered any advantage over the use of plain cotton-wool swabs in preserving beta-haemolytic streptococci during storage for periods up to 48h. Storage temperature of swabs did however have a profound effect on survival of organisms. The prevalence and significance of group B streptococci (GBS) in the upper respiratory tract of a group of Edinburgh schoolchildren was investigated. During the period of study a number of sampling and laboratory techniques for the isolation and identification of GBS were compared. The overall carriage rate of beta-haemolytic streptococci in the throats of the children sampled and the role of this area in the isolation of GBS is discussed. A new commercially-available kit for the identification of beta-haemolytic streptococci was compared with the standard 'Lancefield' technique for grouping streptococci. In addition, a system of streptococcal grouping based on a modified enzyme-linked immunosorbent assay (ELISA) is presented. The value of this technique was assessed against the two previously mentioned systems. A degree of difficulty in obtaining the required specificity in the ELISA studies prompted further investigations into the immuno-chemical character of the cell wall of strains of GBS. Unlike many previous studies, cell walls were collected and purified by sodium dodecyl sulphate (SDS) treatment and the secondary wall polymers were separated from the peptidoglycan component by avariety of procedures. Extracted antigens were visualised by reacting with specific antisera in a crossed inmunoelectrophoresis system. Further purification of antigen complexes were achieved by chromatographic methods and chemical analysis was performed using paper and gas-liquid chromatography. The relevance of the specific antigen complexes isolated from GBS cells in relation to serological grouping and typing methods is discussed. Comment is made on the possibilities of further applications of these studies.