SQL Case statement not return under FALSE

From what you posted the only way it will never get to the else is if [Parse_Row4] is NEVER null.

Don't confuse empty strings as nulls.  Possibly:  Case When trim([Parse_Row4]) is not null

We'll need more information.  Sample data and expected results would help a LOT!

Just a thought..   ISNULL([Parse_Row4], [Parse_Row2])   does the same thing.

And of course slightwv is correct regarding...

• empty strings ' ', which are still a value, different from NULL which is the absence of a value. 
• Give us your full T-SQL statement and some sample data. 

the easiest way is to compare the field values side by side:

[Parse_Row4] , Parse_Row2] ,
Case When [Parse_Row4] is not null  Then [Parse_Row4] Else [Parse_Row2]   End 

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what's your expected result for the False condition?

could the False condition returns the same value as True condition as well? like NULL, etc?

I tend to agree with the experts above in so much as checking for NULL is often not enough.

I would be inclined to check LEN

ie  case when len(isnull(Parse_ROW4,'')) > 0 then Parse_ROW4 else Parse_ROW2 end as result

Just to test....

create table #EE_TEST (Parse_ROW4 varchar(20), Parse_ROW2 varchar(20))

insert #EE_TEST values (null,'2a')
insert #EE_TEST values ('4b','2b')
insert #EE_TEST values (' ','2c')

select Parse_ROW4, Parse_ROW2, len(Parse_ROW4) as Len_Parse_ROW4,
       case when len(isnull(Parse_ROW4,'')) > 0 then Parse_ROW4 else Parse_ROW2 end as result
from #EE_TEST

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Or, am I missing something else ? It almost sounds like it is only ever returning the TRUE condition, meaning Parse_ROW4 is never null.... In which case are there other conditions in you query that *might* be impacting your case condition.