Alternate row colours angular material table

Use Following CSS in your .css or .scss file to set the different style for even/odd row:

.mat-row:nth-child(even){
    background-color: red;
}
        
.mat-row:nth-child(odd){
    background-color: black;
}

Updating this answer with a newer approach to future developers who may come to this question.

Material Angular now offers some variables to row indexes.

<mat-row *matRowDef="
              let row;
              let even = even; 
              columns: displayedColumns;" 
         [ngClass]="{gray: even}"></mat-row>

In you CSS file: .gray { background-color: #f5f5f5 }

There are other properties like: index, count, first, last, even and odd.

You can find out more on Angular Docs, more specifically on section "Table showing each row context properties"