The influence of military service on self-assessed hearing symptoms and measured auditory function was studied as well as the efficacy of the Hearing Conservation Program (HCP) of the Swedish Armed Forces. 839 conscripts were recruited for the study at reporting to military service. They were all exposed to noise over the risk-limits from weapons and vehicles and used earmuffs and/or earplugs. Questionnaires and pure tone screening audiometry were studied at the start and the end of the military service. Retrospective information regarding audiometry at conscription before military service was included as control. The prevalence values of tinnitus were 23% before and 32% after the service and of sensitivity to noise 16% and 19% respectively. The prevalence values of hearing impairment were 6.3% at conscription, 14.5% at reporting to military service, and 24% after the training period. The incidence values of hearing decline were 3.7% during the period with no military noise exposure and 6.6% during the military service. Acoustic accident increased the risk of worsened tinnitus and sensitivity to noise four times and for a high frequency hearing decline six times. We observed elevated prevalence values of tinnitus, sensitivity to noise and hearing impairment at discharge compared to before military service. We observed an elevated risk of hearing decline during military service. Acoustic accident increased the risk of tinnitus, noise sensitivity and hearing decline. We suggest improvements regarding inclusion criteria for military service, and for education regarding the HCP.