Cyanoaclyrate (CA) fuming has commonly been used to detect latent fingerprints and was reported in most cases not to adversely affect short tandem repeat (STR) typing. However, the effect of the CA fuming on DNA extraction efficiency was not reported. In this study, the DNA quantity of CA-fumed samples was measured by real-time PCR assay and STR typing was performed. Twenty microliters of saliva and 3 μl of blood were smeared on glass slides and polyethylene terephthalate (PET) sheets. The samples were treated with (1) CA, (2) CA and ultraviolet light (UV, 254 nm) irradiation, and (3) CA, 7-benzylamino-4-nitrobenz-2-oxa-1,3-diazole (BBD) and Polilight (450 nm) irradiation. The amounts of DNA extracted from the samples were quantified using real-time PCR assay and STR typing was performed. The saliva samples on the glass slides were covered with a large amount of CA, and the average of their DNA concentrations was reduced to 0.43 ng/μl, while that of non-treatment control was 0.75 ng/μl. Similar results were obtained from the saliva samples on the PET sheets. A Double swab technique did not improve the recovery of the DNA quantities. On the other hand, blood samples that were hardly covered with the CA had almost the same DNA quantities as those of the non-treatment control. Concerning the post treatment methods, the UV irradiation drastically reduced the DNA quantities, but the BBD and the Polilight hardly reduced them. Full STR profiles were obtained from all of the saliva and blood samples except for the samples irradiated with the UV. Ten PET bottle samples were fumed with the CA gas as the simulated casework samples, and full STR profiles were obtained from 8 out of 10 samples. In conclusion, DNA quantity of saliva samples was reduced by CA fuming probably due to the covering of a large amount of the CA; however, the CA fuming did not affect STR typing adversely.