The Diagnostic Semi-solid Salmonella Agar (DIASALM) was compared with two commercial semi-solid Rappaport-Vasiliadis media (MSRV by Oxoid and SRVA, basis by HiMedia) using 52 strains of Salmonella and 10 strains of interfering Gram-negative bacteria. The diagnostic potency for salmonellae was higher in DIASALM than in MSRV or SRVA. Unlike the Rappaport-Vasiliadis media, DIASALM contains a diagnostic system consisting of lactose, saccharose and bromocresol purple, allowing the differentiation of salmonellae from non-pathogenic Gram-negative sugar-fermenting bacteria (Tab. I). The semi-solid media were supplemented with 0.0015% nitrofurantoine to recover specifically Salmonella enteritidis. Eighty percent of strains of the latter serovar were resistant to this chemotherapeutic agent, while all the other serovars were sensitive to it. The use of discs soaked with the monovalent Salmonella antiserum H:g,m increased the recovery rate in 95 percent of S. enteritidis strains. Compared with the cultures from peptone water, the diameters of the migration zones formed by the positive cultures grown in M-broth were larger by 3 to 5 mm. Pure cultures of salmonellae were isolated in 98% of cases from the borders of the migration zones when mixed cultures of salmonellae (a S. enteritidis isolate from a patient, density 10(3) to 1 or 2 cells per drop) and Citrobacter koseri or Edwardsiella tarda, or Proteus mirabilis, or Psedomonas aeruginosa (densities > or = 10(3) cells per drop) were inoculated onto DIASALM (Tab III).