We present observations of slowly evolving, balloon-type solar mass ejections observed by the LASCO coronagraphs aboard SOHO. These mass ejections are typically observed to rise gradually in the solar corona for several hours (>20 hours) as large loops or balloons crossing the entire field of view of the coronagraphs. Usually, their angular extent does not change much. Analysis of several such cases of balloon-type mass ejections show that they rise with very slow speeds (less than 50 km s−1) up to a distance of2&hthinsp;R⊙and then are accelerated to higher speeds until5&hthinsp;R⊙.From a distance of about20&hthinsp;R⊙,the mass ejecta attain almost a constant speed ranging between 300 and 500 km s−1. The speed profiles obtained for individual mass ejections indicate that they trace out the slow solar wind and, thus, provide an insight into the initiation and the propagation of the CMEs into the solar wind. ©1999 American Institute of Physics.