int i = 0; Form2 frm; public Form1() { InitializeComponent(); timer1.Enabled = true; } private void timer1_Tick(object sender, EventArgs e) { this.textBox1.Text = ""; this.textBox1.Text = "Timer ticked event called " + i + " times"; i++; if (frm != null) frm.textBox1.Text = this.textBox1.Text; } private void button1_Click(object sender, EventArgs e) { frm = new Form2(); frm.textBox1.Text = this.textBox1.Text; frm.Show(); }