Background: Researchers willing to publish their interventional studies' results must register their studies before starting enrollment. This study aimed to describe all "open" (i.e., recruiting or not yet recruiting) behavioral studies in 16 of 20 top worldwide leading causes of death. Method: Search on Clinicaltrials.gov database (March 2010). Results: Of 204 studies, 66% accounted for the following diseases: diabetes (26%), colon and rectum cancers (16%), cerebrovascular diseases (14%), and HIV/AIDS (11%). Less than 3% were on tuberculosis, stomach cancer, cirrhosis of the liver, and lower respiratory infections combined; no study was open on malaria, nephrosis and nephritis, and diarrheal diseases. A total of 81% of the studies were interventional, and 19% were observational. Fifty-nine percent were conducted in the United States. A total of 79%, 35%, and 5% were sponsored by universities, U.S. federal agencies, and industry, respectively. Twenty-one percent of studies were cofunded. A typical interventional study had a two-arm prospective parallel design, lasting approximately 3 years and involving 100 to 400 subjects. Conclusions: Increasing the number of trials and participating countries (including developing ones) is necessary to make available behavioral interventions in different settings in the future. (Contains 5 tables.)