Objective To diagnosis tumor transplanted nude mice Strongyloidiasis. Methods Postmortem microscopic examination of the tumor transplanted nude mice detected Strongyloides stercoralis for morphological identification and double polymerase chain reaction (PCR) assay for molecular diagnosis of Strongyloides stercoralis infection in tumor transplanted nude mice. Results Presence of numerous S. stercoralis in autopsy in tumor transplanted nude mice samples preliminary determined the diagnosis of strongyloidiasis. Confirmed diagnosis of Strongyloides stercoralis infection by double PCR detection of specific DNA in tumor transplanted nude mice samples. Conclusion The most important clue to prevent such serious consequences is early diagnosis. Tumor transplanted recipients and donors should be screened for parasitic infections including strongyloidiasis. To the authors' knowledge, this study is the first extensive report on diagnosis tumor transplanted nude mice Strongyloidiasis.