Data readability in our grid control be improved significantly using alternating styles.
If you have not applied skin for the grid control, you can modify directly the ItemStyle/AlternatingItemStyle properties of the control:

• ItemStyle - for odd rows
• AlternatingItemStyle - for even rows

In case you have enabled a skin, you will need to modify the GridRow_[SkinName]/GridAltRow_[SkinName] css classes in the RadControls/Grid/Skins/[SkinName]/Styles.css file. For the Default grid skin these classes look like this:

.GridRow_Default td
{
background: #f7f7f7;
line-height: 22px;
border: solid 1px #f7f7f7;
border-top: solid 1px #e9e9e9;
border-bottom: solid 1px white;
padding-left: 4px;
/*add more definitions here*/
}

.GridAltRow_Default td
{
background: #f7f7f7;
line-height: 22px;
border: solid 1px #f7f7f7;
border-top: solid 1px #e9e9e9;
border-bottom: solid 1px white;
padding-left: 4px;
/*add more definitions here*/
}

More information about how to modify existing skins you can find in the topic from the product online documentation linked below:
Modify existing skins