Complement fixation test reactions to the following viruses were studied in 372 samples (I57 rodents, I72 domestic animals, 43 persons) from Pakisran: Bunyaviridae, Phlebovirus: Phlebotomus fever Sicilian (PFS), Phlebotomus fever Naples (PFN), Karimabad (KAR), Salehabad (SAL); Nairovirus: Crimean-Congo haemorrhagic fever (CCHF), Hazara (HAZ), Dera Ghazi Khan (DGK), Dhori (DHO); Uukuvirus: Manawa (MWA); ''possible members'': Bakau (BAK), Bhanja (BHA). Reoviridae, Orbivirus: Wad Medani (WM). Unclassified: Wanowrie (WAN). Four of these viruses are Phlebotomus-borne (PFS, PFN, KAR, SAL). The other nine are tick-borne. Antibodies against each virus were detected in sera from rodents. Antibodies against PFS, PFN , KAR, CCHF, DGK, BHA, WM and WAN viruses were detected in sera from domestic animals. Antibodies against PFS , CCHF, DGK, DHO, MWA, BHA, and BHA and WAN viruses were detected in human sera. The presence in Pakistan of KAR, DHO, BHA, and WAN viruses is documented for the first time. Over-all prevalence rates were highest for BHA (12. I%) and WM (IO.7%) viruses, followed by DGK, CCHF, PFN and PFS (4.0 to 5.4%) and DHO, KAR, WAN, SAL, MWA, BAK and HAZ (0.3 to 2. 1%). Epidemiological factors relating to virus circulation and human disease are discussed.