The fluxes and fate of different forms of anthropogenic nitrogen (N) inputs in tropical forest soils are poorly understood. I applied ¹⁵N pool dilution and tracer techniques to understand the flows of inorganic N in the surface soils of three tropical forests varying in substrate age and fertility in the Hawaiian Islands. Nitrogen limits tree growth at the 300 year old substrate site, neither N nor P limit tree growth at the 20,000 year old site, and P limits tree growth at the 4.1 million year old site. Leachates collected after 24hr showed that less that 2% of the ¹⁵N added as NH4⁺ at tracer levels of N (0.05g/m²) was lost as solution loss at the 300 and 20,000 year old sites; losses were higher but more variable at the 4.1 million year old site. Losses as NO3^- as a fraction of the ¹⁵N added as NH4⁺ were very low at the N-limited site whereas they represent 42% of the ¹⁵N added at the 20,000 year old site and 4% at the 4.1 million year old site. Additions of ¹⁵NH4⁺ at elevated levels (0.5 g/m²) resulted in higher losses as NH4⁺ (11-28% of N added) and NO3^- (10-20% of N added). Solution losses as nitrate under tracer and elevated levels of N were relatively high at all sites representing 33- 70% of the N added as ¹⁵NO3 . Findings from this study suggest that leaching loss responses to N additions in the tropics will vary as a function of soil age, nutrient status, and the form of N added.