We studied adherence and chemotaxis of peritoneal neutrophils from rats fed a diet providing 0.3, 3 or 10% of the energy as linoleic acid. Whereas neutrophils from the 0.3% group showed biochemical evidence of essential fatty acid deficiency (EFAD), cells from the 10% group (the high essential fatty acid (HEFA) group) exhibited a 38% increase of linoleic acid compared to the control group (3% group). EFAD neutrophils showed a significantly lower hyperadherence in response to the ionophore A23187 relative to controls. Also, the fMLP induced response was slightly lower, whereas adherence responses to PMA were unaffected. fMLP induced chemotaxis was only 42% of controls. In HEFA neutrophils, hyperadherence to PMA was significantly diminished, and fMLP or ionophore A23187 stimulation resulted only in a slightly lower hyperadherence compared to controls. Chemotaxis in response to fMLP was significantly decreased. Spontaneous adherence and migration as well as hyperadherence and chemotaxis in response to LTB4 did not differ from controls for any of the groups. This study shows that manipulation of the dietary content of linoleic acid can alter neutrophil functions such as adherence and chemotaxis.