Muscle wasting and loss of function are key features of cancer cachexia. Systemic inflammation (SI) is believed to play a central role in driving muscle loss and is also associated with poor survival in cancer (Deans et al, 2009). We hypothesized that muscle strength and power would be lower in cancer patients at the time of diagnosis compared with UK population data (Skelton et al 1994; 1999), and that strength, power and muscle quality (defined as strength per unit muscle volume Nl,^-1) would be influenced by the presence of systemic inflammation (defined as C-reactive protein (CRP) > 10mgl,^-1). Twenty five patients with a new diagnosis of upper GI (UGI) cancer, (15 men, 10 women; mean age 66y), (mean) weight loss 8% and CRP 22mgl^-1 participated. Lower limb power output (Nottingham power rig) and maximum voluntary isometric knee extensor strength were measured pre-operatively. In a sub-group of patients (n=12), sequential T1 weighted axial magnetic resonance (MR) images were acquired using a 1.5T MR scanner and analysed off-line for quadriceps muscle volume and derived measures of muscle quality. Statistical analysis to determine group differences was by Mann-Whitney and independent t-tests. Mean (SD) maximum voluntary isometric knee extensor strength was 3.68Nkg^-1 (1.15) in males and 3.36Nkg^-1 (0.96) in females. Mean lower limb power output was 1.53Wkg^-1 (0.43) in men and 0.98Wkg^-1 (0.28) in women. Muscle power output and isometric strength were 42% (p<0.001) and 35% (p<0.001) below UK age- and sex-matched reference values. The differences between measured and reference values of power and strength were significantly greater (p<0.008; p<0.047 respectively) in the presence of SI. Muscle quality was also significantly reduced in patients with SI compared to those without SI, (147.8Nl^-1 vs 268.1Nl^-1, p=0.017). We conclude that at the time of diagnosis, muscle function in UGI cancer patients is already impaired. The magnitude of the impairment appears to be greater in the presence of SI. These data provide a rationale for targeting early therapeutic intervention to improve muscle function in cancer cachexia.