We established the occurrence and distribution of begomoviruses in Kenya. Field survey was conducted in major sweetpotato growing regions (i.e., Western, Nyanza, Coast, and Eastern). A total of 896 samples were collected and tested by PCR to confirm begomoviruses. One hundred and sixty-seven (167) tested positive from the different regions. Rift Valley had the highest level of infection at 47%, Western – 16 %, Nyanza – 19 %, Coast – 11 %, Eastern – 10 % and Central – 12 %. Two seasons of a field trial using virus tested and virus infected plants of varieties ‘Kakamega’ and ‘Ejumula’ were conducted to establish effect of begomoviruses by themselves or in combination with common viruses on yield.