Abstract We analyzed the productive and economic performances of a constant sample of 58 organic ruminant farms between 2014 and 2018, in a mountain grassland area (French Massif Central). Over this 5-year period, these farms expanded without increasing their labor productivity or animal density per hectare of forage area. While animal productivity has been maintained, we observed a decrease in feed self-sufficiency, and thus, an increase in feed purchases. Over the period, the volume of inputs used has increased more rapidly than agricultural production, resulting in a decline in the productivity surplus (PS) at a rate of −2.6%/year. As the prices of products and inputs were relatively stable, this decrease in PS was financed at 41% by an increase in public aid (drought aid, agri-environmental climate measures) and at 49% by a decrease in profitability for the farmer (the farm income per farmer fell by 40%). A binary choice estimation model, i.e., which variables determine the positive or negative sign of the PS, showed that farm size was a negative determinant of the PS, as was system specialization, while feed self-sufficiency was a positive determinant. More statistically robust references on price indices of organic farming (OF) products and inputs, as well as long-term follow-ups of OF farms, are needed to validate these original results, which were based on a small sample size and a short period of time.