Abstract: "This paper reports the level of serum Igs(G, A, M) in coventional NIH, BALB/ c mice of different ages and sex detected by routine radialitnmunodiffusion (SRID) and rate scatted nephelometry. The level of serum Igs (G. A. M) of mice increased with age. The content of IgG was 10.73 mg/ml, IgA 0.41 mg/ml, IgM 0.82 mg/ml in NIH mice and IgG 7.74 mg/ml, IgA 0.34 mg/ml, IgM 1.35 mg/ml in BALB/c mice at the age of two months, then the level continued to rise steadily. After 6 months IgG of NIH mice and IgM of BALB/c mice continuely increased, the others tended to decline. Except IgM there was a significant difference between sex at 6-12 months of age. no significant difference in the other ages of two strain of mice. The results obtained from SRID and nephelometry were corralated well (IgG r =0.931,IgA r = 0.861).The level of serum Igs(G. A. M) among 5 different strains of mice at two month ages was detected by rate scatted nephelametry. In different strains, no significant difference was noted in IgA level. The level of IgG in BALB/ c mice was the lowest and the level in kunming was the highest. The IgG level ranged from 9.16-10.73 mg/ml in the other 3 strains. In addition, IgM of DBA/2 mice show a significant difference bdtween sex among 5 strains, (t=3.5051 p<0.05). The present study established Igs criteria of mice in body fluid immune function and provided experimental reference data of mouse body fluid responce in experimental immunology and pharmacological immunology."