Although many studies have assessed the effects of water pollution on amphibians, few have focused on the alteration of vital behaviors. Newt species usually display complex courtship behavior that may be altered by sublethal levels of contaminants. We analyzed the effects of ammonium nitrate and water acidification on courtship behavior of the Iberian newt (Lissotriton boscai). We exposed newt couples to three treatments (control, nominal 90 mg N--NO3NH4/L, and nominal pH 4) and recorded the occurrence of each of the three courtship phases (orientation, static display, and spermatophore transfer) as well as the latency to initiate courtship, overall courtship time, male perseverance, and female responsiveness. Major effects were observed in the acid treatment. Low pH inhibited orientation. None of the control couples failed to court, whereas 17% of couples from the low-pH treatment did not perform any courtship movement. Latency to initiate courting was twice as high in couples exposed to acidification as in controls. Low pH also affected the overall time of courtship and perseverance time of males in unsuccessful encounters. Ammonium nitrate did not cause any significant effect. Only the female response index and the duration of the tail-fanning movement (the major display during L. boscai courtship) were slightly reduced by the fertilizer. We report a pollution-mediated alteration of courtship behavior, to our knowledge for the first time, in amphibians. This kind of sublethal effect should be considered when estimating potential impacts of water pollution on natural populations.