This study was conducted to investigate the effects of n-6:n-3 polyunsaturated fatty acid (PUFA) ratios on serum protein and immunoglobulins in growing geese. One hundred and sixty healthy Yangzhou geese were randomly divided into 4 groups: diets were designed as 12:1, 9:1, 6:1, and 3:1, respectively, by varying dietary n-6:n-3 PUFA ratios. Protein and immunoglobulin levels were measured on d 42, d 56, and d 70. The experimental results showed that total protein was highest in group 6:1 on d 42 (P<0.05), albumin, in group 12:1 on d 56 (P<0.05), and globulin, in group 6:1 on d 42 (P<0.05). No significant difference was detected in the albumin/globulin ratio (A/G ratio) among groups (P>0.05); however, the numerical value of the A/G ratio of group 3:1 was higher than in any of the other groups at all sampling ages. On d 56 and 70, IgA and IgM were highest in group 3:1, whereas IgG was highest in group 6:1, and these values were significantly higher than in the other groups (P<0.05). Overall, diets containing low n-6:n-3 PUFA ratios could increase the serum A/G ratio, IgA, IgG, and IgM, in the Yangzhou goose on days 56 and 70.