OBJECTIVES: The aim of this study was to investigate the relationship between symptom severity, cost, and impairment in women with moderate/severe premenstrual syndrome (PMS) or premenstrual dysphoric disorder (PMDD) in a Latin American setting. METHODS: A model was constructed based on analysis of an observational dataset. Data were included from four Latin American countries. Responder-level data were analysed according to four categories of symptom severity: Category 1 comprised Daily Record of Severity of Problems score 21 to 41.9, Category 2 score was 42 to 62.9, Category 3 score was 63 to 83.9, and Category 4 was a score of 84 or higher. Burden was estimated in terms of impact on job and activities using the modified work productivity and impairment questionnaire and affect on quality of life using the SF-12 questionnaire. Costs were estimated in Brazilian reals from a Brazilian private health care and societal perspective. The outputs of the analysis were estimates of burden, mean annual cost and affect on quality of life (as measured by quality adjusted life years) by symptom severity. Confidence intervals around key outcomes were generated through nonparametric bootstrapping. RESULTS: Analysis suggests a significant cost burden associated with moderate/severe PMS and PMDD with mean per patient annual costs estimated at 1618 BRL (95% confidence interval 957-2,481). Although the relationship between cost, quality of life, and severity was not clear, analysis showed a consistent relationship between disease severity and measures of disease burden (job and daily activity). Burden on activities increased with disease severity. CONCLUSIONS: Our analysis, conducted from a Latin American perspective, suggests a significant burden and an increasing impairment associated with moderate/severe PMS and PMDD.