Species of scotochromogenic mycobacteria of Group II isolated from sputa of patients with pulmonary tuberculosis and tuberculosis-like diseases from 1979 to 1984 were identified by simple biochemical tests using. nitrate reduction, Tween-80 hydrolysis, arylsulfatase and urease test, and serotypes of the isolates belonging to M. scrofulaceum were differentiated by bacterial agglutination test. Of 39 strains. tested, 11(28.2%) proved to be M. scrofulaceum, 15(38.5%) M. flavescens and 13(33.3%) M. gordonae. But none of the isolates belonged to M. szulgai and M. xenopi known as major pathogens of mycobacteria of Group II. Of 11 strains of the isolates identified as M. scrofulaceum 3 strains(27.3%) each belonged to serotype 41 and 42, and 4 strains(36.4%) belonged to serotype 43, but one strain was not typable because of its inagglutinability by any one of the type specific sera. In addition, the sensitivity and specificity of rabbit immune sera against type strains of serotype 41, 42 and 43 of M. scrofulaceum were analysed by bacterial agglutination test. In the sensitivity of microplate test with 11 isolates of M. scrofulaceum, a comparative tandem test using 2 units and one unit of absorbed antisera against three serotypes appeared to be superior to a conventional microplate test using one unit of type specific antisera.