A total of 656 lung specimens comprising 196 grossly pneumonic lungs from clinically diseased pigs and 230 grossly pneumonic and normal lungs from abattoirs were cultured for mycoplasmas. Mycoplasmas or acholeplasmas were recovered from 102 lung specimens, of which 28 were serologically identified (by disc growth inhibition and agar gel diffusion tests) as Mycoplasma suipneumonia, 14 as M hyorhinis, 35 as Acholeplasma granularum and 4 as A laidlawii. In addition, 15 isolates were unclassified and six were not typed. Mycoplasmas isolated from the suspect enzootic pneumonic lungs: slaughterhouse pneumonic lungs: normal lungs were in the ratio of 3:2:1. M suipneumonia, A granularum and A laidlawii were isolated from both normal and pneumonic lungs of pigs while M hyorhinis was only isolated from pneumonic ones. A close antigenic relationship between M suipneumonia and A granularum was demonstrated.