The aim of this study was to analyze the association between serum concentrations of immunoglobulins (Ig) A, G, and M and body composition of adolescents from Mexico. Informed consent was obtained from parents and assent was obtained from the adolescents for the evaluation of 125 adolescents from the Capital city of Toluca and the adjacent semiurban county of Lerma de Villada. Height, weight, waist, and hip circumference were measured by trained personnel. Body mass index and waist:hip ratio were calculated from these measurements, whereas body fat (BF) was calculated from tricipital and subscapular skinfolds and measured by bioelectrical impedance. Serum concentrations of Ig were determined by nephelometry. Data were analyzed by independent samples t test and Pearson correlations. Subjects were mainly females (71.2%), with a mean age of 16.8 years (+/-0.8). No differences were reported in all indicators by weight or BF between gender. Female participants had higher Ig concentrations than males (IgG t = 2.24, p = 0.027; IgA t = 2.05, p = 0.043; IgM t = 4.49, p < 0.001). Positive correlations were reported for IgA and IgM with tricipital skinfold (r = 0.192, p = 0.041; and r = 0.221, p = 0.018, respectively) and for total BF by bioimpedance (r = 0.243, p = 0.009). Ig concentrations do not seem to be affected by overweight, obesity, or excessive or central BF in adolescents.