Fifty five strains of group F streptococci (GFS) isolated from clinical samples of 53 patients with diverse diseases, were characterised by a battery of physiological tests. Among them 37 (67%) were Streptococcus anginosus F, 14 (25%) were Strep. intermedius, two of which were mannitol positive and 4 (7%) were Strep. constellatus. Determination of minimum inhibitory concentrations of penicillin, erythromycin, ampicillin, gentamicin and cefazolin showed that despite their biochemical heterogeneity, all strains were uniformly susceptible to these antibiotics. Except for bacteraemia, other diseases due to GFS responded well to surgical drainage and/or antibiotics.