OBJECTIVE: To evaluate changes in Duchenne muscular dystrophy to spermatogenesis in an mdx mouse model. STUDY DESIGN: Eight C57BL/10 (non-dystrophic control) and 8 C57BL/10Mdx (dystrophic) lineage were distributed into 4 groups: (1) Control group 30 days old (C30), (2) Dystrophic group 30 days old (D30), (3) Control group 60 days old (C60), and (4) Dystrophic group 60 days old (D60). The mice were euthanized, and testes were removed and weighed, fixed in Karnovsky fixative or 2.5% glutaraldehyde (for histology and transmission electron microscopy, respectively), sectioned, and stained with toluidine blue/sodium borate for morphological characterization and morphometric analyses. RESULTS: A higher percentage (p≤0.05) of tunica propria was present in D30 (5.84±0.66, mean±SD) as compared to C30 (2.27±0.34) or D60 (3.74±0.52). Dystrophy did not alter morphology of germinal epithelium cells, thus raising the overall efficiency of spermatogenesis in D60 (27.70±1.49) when compared to C60 (24.03±1.74). CONCLUSION: Although muscular dystrophy caused testicular damage, even in prepubertal mdx mice, it did not prevent spermatogenesis. © Science Printers and Publishers, Inc.