The author presents acute appendicitis with atypical localization of appendix in hernial sac in a patient with right-sided inguinal hernia. Long-standing disease (3 days), progressive destructive process in appendix (gangrenous-perforative appendicitis) led to spread of infection beyond the hernial sac and development of local inflammatory process in inguinal tissues. Surgical team recognized this pattern as a complication of strangulated right-sided inguinal hernia (hernia sac phlegmon). Despite the diagnostic error, timely surgical intervention and adequate tactical approach contributed to a favorable outcome.