Indirect haemagglutination tests on sera from 757 South American camelids (alpacas, llamas and vicunas) carried out in the Andean region of Peru, revealed evidence of exposure mainly to Mycoplasma mycoides subspecies mycoidesLC. The incidence of detectable antibodies to this mycoplasma in 554 alpacas was 5·0 per cent and in 141 llamas 15·6 per cent. Antibody to Mycoplasma capricolum and the F38 biotype was detected in 0·9 per cent and 0·2 per cent of alpacas, respectively. In a group of 62 vicunas only one reactor to both M m mycoidesLC and M capricolum was observed. No reactors to M mycoides subspecies capri or M agalactiae were observed in the flocks examined. Antibodies to mycoplasma were also detected in nine out of 10 goat flocks tested. The incidence of antibodies to M m mycoidesLC was 13·8 per cent, 3·8 per cent for M capricolum and 1·8 per cent for the F38 biotype. In a group of 110 sheep, six reactors (5·5 per cent) to M m mycoidesLC and one (0·9 per cent) to F38 were observed. The implications of these results are discussed in relation to the involvement of mycoplasmas in existing disease in camelids in Peru. © 1991.