 <p>Try This:</p> <pre><code> int maxNo = 4; //you can change this no and logic works till 9 comboboxes void clearPreceding(ComboBox cmbBox) { int cmbBoxNo = Convert.ToInt32(cmbBox.Name.Substring(cmbBox.Name.Length - 1)); for (int i = cmbBoxNo; i &lt;= maxNo; i++) { ((ComboBox)this.Controls.Find("comboBox" + i, true)[0]).Text = ""; } } </code></pre> <p>You can Subscribe to One EventHandler for all Combobox's <code>SelectedIndexChanges</code> Event as below:</p> <pre><code> comboBox1.SelectedIndexChanged += AllCombobox_SelectedIndexChanged; comboBox2.SelectedIndexChanged += AllCombobox_SelectedIndexChanged; comboBox3.SelectedIndexChanged += AllCombobox_SelectedIndexChanged; comboBox4.SelectedIndexChanged += AllCombobox_SelectedIndexChanged; </code></pre> <p>and the EventHandler is:</p> <pre><code> private void AllCombobox_SelectedIndexChanged(object sender, EventArgs e) { clearPreceding((ComboBox)sender); } </code></pre> <p><strong>Complete Code:</strong></p> <pre><code>public partial class Form1 : Form { int maxNo = 4; public Form1() { InitializeComponent(); comboBox1.SelectedIndexChanged+=AllCombobox_SelectedIndexChanged; comboBox2.SelectedIndexChanged += AllCombobox_SelectedIndexChanged; comboBox3.SelectedIndexChanged += AllCombobox_SelectedIndexChanged; comboBox4.SelectedIndexChanged += AllCombobox_SelectedIndexChanged; } private void AllCombobox_SelectedIndexChanged(object sender, EventArgs e) { clearPreceding((ComboBox)sender); } void clearPreceding(ComboBox cmbBox) { int cmbBoxNo = Convert.ToInt32(cmbBox.Name.Substring(cmbBox.Name.Length - 1)); for (int i = cmbBoxNo; i &lt;= maxNo; i++) { ((ComboBox)this.Controls.Find("comboBox" + i, true)[0]).Text = ""; } } } </code></pre>