with the CLR 2.0 nullable types, this is now well defined: <font size="2">DateTime? nullDate = null; // nullable type DateTime minDate = DateTime.MinValue; nullDate == null     // true nullDate < minDate   // false nullDate > minDate   // false nullDate == minDate  // false nullDate != </font><font size="2">minDate  </font><font size="2">// true DateTime? someOtherNullDate = null; nullDate == someOtherNullDate    // true</font> This lets you define the semantics of the value null for your variables.