<p>I am looking to find out the logic , if any , which shrinks hashtable in c# when elements are removed from it.</p>

<p>Regards
Harish</p>

The only indication of size changes for a hashtable in the documentation is when the load factor is exceeded and the size of the hashtable is increased.  There is no mention of a hastable ever shrinking.
There is some further detail of the load factor on
MSDN
.