Abstract: Objective To evaluate the stablity of homemade PPD.Methods Prepare 1506 babies immuned from BCG.Use PPD in useful life as contrast of four groups of PPD which is stored in four condition:2～8℃ in refrigeratory;60℃ keeped as long as 30 minutes then 2～8℃ in refrigeratory;36℃in the constant temperature box;room temprature.Test the 4 kinds of PPD on both arms of the babies,and watch them for three years to find out how much that different temprature affects PPD’s sensitivity.Results Noting the positive ratio and induration pattern of the delayed allergic reaction on the babies with the test PPD then compare them to te PPD which in useful life.The result comes out:the group of in 2～8℃ refrigeration is normal (P>0.05) but other three groups show remarkable different (P<0.01).Conclusion Homemade PPD owns steady quality and nice safety,if stored in 2～8℃ condition PPD suseful life can be delay to 3 years considerable.

Key words: PPD, BCG, Stability