Eighteen species of the genus Leptonema (Trichoptera: Hydropsychidae: Macronematinae) are reported from Costa Rica. In this paper, five additional undescribed species of Leptonema from Costa Rica are diagnosed, described and illustrated: L. clorito, L. flintorum, L. huismanae, L. rafita, and L. tapanti. Their distribution records in Costa Rica are mapped. Also, L. cheesmanae Mosely is illustrated and recorded from Costa Rica for the first time.