Background: There is evidence that Sudarshan Kriya Yoga (SKY) has significant antidepressant effects. Objective: The present study examined whether pretreatment P300 ERP amplitude predicts antidepressant response to SKY. Methods: Consenting, drug-free depressed patients (n = 30; dysthymics, 15, melancholics, 15) who received SKY as the sole treatment were assessed clinically at pretreatment, 1 month and 3 months. Auditory P300 was recorded before treatment. Results: Twenty-two patients responded favourably to SKY. The pretreatment P300 amplitude neither distinguished responders and non-responders nor was associated with differential rates of response. Discussion: It is concluded that SKY therapy is uniformly effective regardless of the pretreatment P300 amplitude. (C) 1998 Elsevier Science B.V.