Background: Multimorbidity is a public health problem with high prevalence and important consequences. The aim of this paper was to verify the prevalence and distribution of multimorbidity in Brazilian older adults.Methods: A population-based survey was carried out in 2008 through face-to-face interviews with 1593 older adults (aged 60 or over) living in Bagé, a medium-sized city in Southern Brazil. Multimorbidity was evaluated by 17 morbidities and operationalized according to two cutoff points: 2 or more and 3 or more morbidities. Descriptive analysis examined the occurrence of multimorbidity by demographic, socioeconomic and health services variables. Observed and expected dyads and triads of diseases were calculated.Results: From total sample, 6 % did not have morbidities. Mean morbidity was 3.6. Morbidities showing higher prevalence were high blood pressure - HBP - (55.3 %) and spinal column disease (37.4 %). The percent of participants with multimorbidity was 81.3 % (95 % CI: 79.3; 83.3) for 2 or more morbidities and 64.0 % (95 % CI: 61.5; 66.4) for 3 or more morbidities. In both measures occurrence was higher among women, the more elderly, less socioeconomic status, the bedridden, those who did not have a health private plan, those who used health services and those living in Family Health Strategy catchment areas. We found 22 dyads of morbidities with prevalence 10 % or more and 35 triads with prevalence 5 % or more. The most prevalent observed pair and triplet of morbidities were HBP and spinal column disease (23.6 %) and HBP, rheumatism/arthritis/arthrosis and spinal column disease (10.6 %), respectively.Conclusions: Multimorbidity frequency was high in the sample studied, in keeping with percentage found in other countries. The social inequities identified increase the health system challenges for the management of multimorbidity, requiring a comprehensive and multidimensional care. The combinations of diseases can provide initial input to include multimorbidity in Brazilian clinical protocols. [ABSTRACT FROM AUTHOR]