Option Explicit
Sub Remplacer()
Dim Couleur, Chaine, Derlig
Dim Cell As Range
Derlig = Range("B65536").End(xlUp).Row
Couleur = Worksheets("SAISIE").Range("C6").Value
Chaine = Worksheets("SAISIE").Range("E6").Value
Sheets("Base").Select
For Each Cell In Range("B1:B" & Derlig)
If Cell.Value = Couleur Then
Cell.Offset(0, -1) = Chaine
End If
Next Cell
End Sub