We present the first study of the orbital period variations of five neglected Algol-type eclipsing binaries TT And, V342 Aql, RW Cap, Z Cas and TW Lac, using their O-C diagrams gathered from all available times of eclipse minima. These O-C diagrams indicate that term periodic variations superimposed on secular period increases as expected in mass transferring Algols. However, due to short me coverage of the data, the secular period increase is not clear in the case of BZ Cas and V342 Aql. The secular period increase is.terpreted in terms of the combined effect of mass transfer between the components of the system and the mass loss by a stellar wind on the system. The mass transfer rates from the less massive secondary components to the more massive primaries for non-conservave cases would be about 10(-7) M-circle dot/yr and 10(-8)M(circle dot))/y for RW Cap and V342 Aql, respectively, and 10(-9)M(circle dot)/yr for TT And and TW . Therefore, the Algol systems RW Cap and V342 AqI have the largest mass transfer rate, which could be in Case AB type, while tose of the Algol systems TT And and TW ' Lac display the slow mass transfer rate and they could be in Case B type. The sinusoidal -rms of the orbital period variations of all five Algol systems can be due to either by the light-time effects due to unseen components in iese systems, or by the cyclic magnetic activity effects of the cool secondary components. The possible third bodies in all five Algol binaes would have masses larger than one solar mass. If these hypothetical large massive third bodies were normal stars, they should be Aectable. Therefore, new photometric and spectroscopic observations of these systems and careful analyses of those data are required. otherwise, the cyclic magnetic activity effects of the secondary components could be the basis of a working hypothesis in explaining the,clic period variations of these systems. 2007 Elsevier B.V. All rights reserved.