Phosphorus is a critical macro nutrient for development and yield formation of crops. In Vietnam, the grey degraded soil is often considered as an unfertile soil type with low phosphorus. and other nutrient content. However, this soil has been comprehensively exploited for agricultural purposes, especially in regions that rice, vegetables and other annual crops are intensively cultivated. Continuously supplying fertilizers over years leads to the occurrence of positive balance of phosphorus in the soil. This. paper presents results of a research on actual phosphorus content in the grey degraded soil in Northern of Vietnam. Results show that both total and exchangeable soil phosphorus in most of soil samples are in the "high level". In some areas, such high phosphorus content was found in up to 70 percent of soil samples. Estimation shows that there is about 15 percent of the grey degraded soil in Northern of Vietnam currently has low P content. This situation obviously demonstrates the sign of P accumulation in the grey degraded soil in Northern of Vietnam over time. The soil in the Red river delta typically has higher P content than in Thanh Hoa and other provinces southwards. Results of this research provide a new perception on fertility of the grey degraded soil in Northern of Vietnam. These contribute important scientific bases for further developments of fertilizer recommendations for crops in order to improve agricultural land use and soil environment on this soil.