In the TNG episode *[The Enemy](http://en.memory-alpha.org/wiki/The_Enemy_%28episode%29)*, Worf ends up being the only viable donor available to save the life of an injured Romulan. 

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> Crusher: "Worf, you are the only one who can save his life."  
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>  Worf: "Then he will die."
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Surely a Vulcan would be a superior match for obtaining vital bodily fluids. And with a crew compliment of 1,014 members there wasn't a single Vulcan serving on the Enterprise-D? 

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> Worf: "There is a substance within my cells which you need to survive."  
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>  Patahk: "Then you've come to hear me beg for my life?"  
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>  Worf: "No."  
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>  Patahk: "I would rather die than pollute my body with Klingon filth!" 
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