Device and method for determining a rheological property, such as viscosity or threadability, of mucus include a housing having a circumferential surface defining an opening for receiving a quantity of the mucus, a probe extending within the housing and having a tip for contacting at least a portion of the quantity of mucus, a displacement mechanism for displacing the tip of the probe with respect to the housing, and a measurement unit for measuring a displacement of the tip of the probe. The device and method are especially suitable for determining the rheological property of mammal cervical mucus for determining female fertility.