Form.Size
using System; using System.Drawing; using System.Collections; using System.ComponentModel; using System.Windows.Forms; using System.Data; public class MyFirstWindow : System.Windows.Forms.Form { public MyFirstWindow() { InitializeComponent(); } private void InitializeComponent() { this.Size = new System.Drawing.Size(300,300); this.Text = "MyFirstWindow"; } public static void Main(string[] args) { Application.Run(new MyFirstWindow()); } }