Abstract.Action potentials from olfactory cells in antennae (funiculi) of living tsetse flies,Glossina morsitans morsitansWestwood, were recorded using a surface‐contact technique. Stimuli were the vapours of the seven alkylphenols identified in cattle urine: phenol, 3‐methyl‐, 3‐ethyl‐, 3‐n‐propyl‐, 4‐methyl‐, 4‐ethyl‐, and 4‐n‐propylphenol. In addition, responses to the vapours of 1‐octen‐3‐ol, acetone and dichloromethane were recorded. The phenol‐sensitive cells could be grouped into four subclasses. Subclass, 1, 2 and 3 cells responded to the phenols only, cells of subclass 1 and 2 being activated by these substances, those of subclass 3 inhibited. Cells of subclass 4 were activated to a similar degree by all phenols and by one or more of the other chemicals tested. Subclass 1 cells were strongly activated by the 3‐alkylphenols, whereas subclass 2 cells were most sensitive to 4‐methylphenol. Subclass 3 cells were most strongly inhibited by phenol, and 3‐ and 4‐methylphenol. The results suggest that though individual phenols may be attractive toG. m. morsitans, preference for certain blends of phenols may exist; for example, blends composed of moderate doses of 4‐methylpheno