The problem-solving strategies of family physicians have evolved in response to six features of family practice: the pattern of illness; the undifferentiated and unorganized nature of conditions seen; the early stage at which illness is seen; the family physician's unconditional commitment to patients; his continuing relationship with his patients, and the time pressure under which he works. The effect of these influences is described in terms of the model of the diagnostic process formulated by Elstein et al.(2).