RESUMOObjetivo: Avaliar a associação da gama-glutamil transferase (GGT) com a presença e número de co-morbidades da síndrome metabólica (SM). Casuística e Métodos: Foram estudadas 353 mulheres consecutivamente admitidas num ambulatório de obesidade, com idade de 39,0 ± 11,4 anos e IMC de 41,3 ± 7,3kg/m 2 . Todas as pacientes eram assintomáticas, não tinham história de ingestão excessiva de álcool ou de doença hepática. Pelo critério do National Cholesterol Education Program -Adult Treatment Panel III foi avaliada a presença de SM. Resultados: A freqüência de SM nos pacientes foi de 50,7%. A presença de GGT elevada foi maior nas pacientes com SM em relação às sem SM (32% versus 20,7%; p= 0,05). A média da GGT foi significativamente maior nas pacientes com SM do que naquelas sem SM (52,8 ± 42,3mg/dl; Md: 40,0 versus 40,1 ± 28,8mg/dl; Md: 33,0, p= 0,0001) e naquelas com cada comorbidade isoladamente quando comparado às pacientes sem elas. Nas pacientes com associação de 3 co-morbidades da SM, a média de GGT foi 51,0 ± 39,2mg/dl (Md: 36,0), com 4 foi de 50,8 ± 50,4mg/dl (Md: 40,5) e com 5 foi de 64,8 ± 32,3mg/dl (Md: 61,0) (p= 0,0002). Houve correlação positiva entre glicose, triglicérides e pressão arterial sistólica e diastólica. Conclusão: Observou-se associação da GGT com a presença da SM ou de suas co-morbidades isoladamente em mulheres obesas. Objective: To evaluate the correlation of gamma-glutamyl transferase (GGT) activity to the presence and number of abnormalities of the metabolic syndrome (MS). Subject and Methods: We have studied 353 women consecutively admitted into the obesity outpatient unit, aged 39.0 ± 11.4 years and body mass index 41.3 ± 7.3kg/m 2 . All patients were asymptomatic, had no history of alcohol abuse or liver disease. National Cholesterol Education Program -Adult Treatment Panel III criteria for diagnosing MS were applied. Results: The frequency of the MS was 50.7% in the patients. The frequency of elevated GGT activity was higher in patients with MS than without it (32% versus 20%, p= 0.05). The average GGT concentration in patients with the MS was significantly higher than in non SM patients (52.8 ± 42.3U/L; Md: 40.0 versus 40.1 ± 28.8U/L; Md: 33.0, p= 0.0001). It was also higher in patients with each one abnormality of the MS, when compared to those without it. In patients with association of three abnormalities of the MS, the mean GGT activity was 51.0 ± 39.2U/L (Md: 36.0); in those with four, 50.8 ± 50.4U/L (Md: 40.5); and five, 64.8 ± 32.3U/L (Md: 61.0). There were positive correlations between GGT and glucose, triglycerides or blood pressure (systolic and diastolic). Conclusion: GGT activity was associated to the presence and the number of artigo original