The primary aim was to determine whether the presence of metabolic syndrome (MetS) limits aerobic fitness in patients with schizophrenia. A secondary aim was to investigate the associations between aerobic fitness and MetS parameters. Aerobic fitness (expressed as predicted maximal oxygen uptake) was assessed using the Astrand-Rhyming test. Those with MetS (n = 19) were similar in age, sex, antipsychotic medication use, symptoms, and smoking behavior than those without (n = 31). Estimated maximal oxygen uptake was 21.4% lower (p = 0.001) in patients with MetS than in patients without MetS (29.5 ± 7.4 ml of O2/min/kg vs. 37.5 ± 8.2 ml of O2/min/kg, respectively). The estimated maximal oxygen uptake of the entire sample was correlated with waist circumference, the level of high-density lipoproteins, and fasting glucose. The current study demonstrates that the additive burden of MetS might place people with schizophrenia at increased risk for functional limitations in daily life activities.