Drip irrigation has been linked to a decline in soil structure in some Australian vineyards. The use of poor quality water and the physical pressures associated with irrigation, such as rapid wetting, threaten soil structural stability and may lead to increased soil strength, bulk density and waterlogged conditions. A reduction in plant available soil water and therefore vineyard productivity may follow. The objectives of this study were: 1) to quantify the extent to which soil physical properties have changed due to irrigation; and 2) to identify a timescale for these changes. Soils of different irrigation histories were compared. Soil cores were taken from vineyards and non-irrigated sites in the McLaren Vale and Barossa Valley winegrowing regions of South Australia. Bulk density, water retention, penetration resistance and hydraulic conductivity were measured in both the laboratory and the field. At the Barossa vineyard, irrigation has increased soil strength and bulk density, and reduced saturated hydraulic conductivity. The decline is more pronounced in the older vineyard suggesting that degradation is a relatively slow process. In the McLaren Vale vineyard, regular gypsum application appears to have prevented subsoil degradation. However it was noted that soil physical properties improved along the vine-row with distance from the drippers, suggesting that irrigation has damaged soil conditions despite gypsum application.