Horn growth in the Caprinae is affected by several factors including age and nutrition, and analysis of annual horn increments can be used to interpret past events. We documented patterns of horn growth in male alpine ibexes (Capra ibex ibex) in the central European Alps and analyzed relationships between annual horn increments, weather, and plant phenology in 2 different climatic regions during 1981–1990. Age accounted for 50% of total variance in horn growth in male alpine ibexes 1–6 years of age. Horn growth differed among climatic regions and calendar years. In years with early onset of vegetation growth, horn growth was enhanced uniformly over all age classes in both climatic regions. Horn growth was a function of ambient temperature during March–May and of plant phenology in spring, implicating onset of growth of vegetation and availability of food resources. Duration of growth of vegetation was assumed to be directly related to date of vegetation onset, but further studies are necessary to test this hypothesis.