Requires a helper column...

1. Assuming your groups are in col. B, place a 1 in A1
and copy the following into A2:

=(B2<B1)*(A1<1)+(B2=B1)*A1

Copy this formula all the way down to your last row.

2. Select all the rows with data.
3. Go to Format Conditional Formatting.
4. Under Condition 1, choose "Formula Is" and use:

=$A1=0

5. Press the Format button, click on a color off the
Pattern tab, and press OK.
6. Click Add, Formula Is, and use:

=$A1=1

7. Press the Format button and choose another color.

HTH
Jason
Atlanta, GA

-----Original Message-----
I have an Excel list where the first column identifies a
group, like
1
1
1
3
4
4
6
6
6
Now I want to color the rows of the groups alternating
for better readability.
Group 1 (the rows starting with 1) - red
Group 2 (the rows starting with 3) - blue
Group 3 (the rows starting with 4) - red
Group 4 (the rows starting with 6) - blue
....and so on

The numbers in this list are not in sequence and have
gaps.
The number of rows belonging to a group differs from
group to group.

Any smart and experienced guy out there who can help?
.