Hi

Try the following Array entered formula
=INDEX(A1:B3,MATCH(TRUE,TEXT(C1,"mmm")=TEXT(A1:A3, "mmm"),0),2)

To Array enter or amend, use Control+Shift+Enter (CSE) not just Enter.
When you use CSE, Excel will insert curly braces { } around the
formula. Do not type the braces yourself.

{=INDEX(A1:B3,MATCH(TRUE,TEXT(C1,"mmm")=TEXT(A1:A3 ,"mmm"),0),2)}
--
Regards
Roger Govier

ck13 wrote:
Hi, assuming the following data:
A B
1 31-Dec-2009 50
2 4-Jan-2010 30
3 5-Jan-2010 20

In C, I have the date for the first day of every month e.g. 1-Jan-2010. In
the adjacent cell in D, i need to lookup the value in B for the first number
that occur for that month (in this case 4-Jan and so, the number should be
30). I tried various formula but as there are no 1-Jan in column A, it
returns the value of 50 (31-Dec). Anyone here has a solution for this? Thanks