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The population of Amietophrynus regularis (Common African Toad) was investigated in an on-going monitoring programme and the sexual size dimorphism (SSD) of amplectant individuals studied. Comparison of studies that were carried out in (2007-2009) and repeated in (2011-2012) revealed that there were increases of toad species at the survey sites of Ijebu Oru (25.9%) and Ibapon Oyewole (0.07%) in the 2011-2012 survey whereas there were decreases in the sites of Ijede (-10.9%) and Onidundun (-21.4%). However there was no significant difference between the two surveys (P>0.05, df=3, tcal = -0.304). Habitat loss due mainly to agricultural practices was still the main cause of decline at affected sites. Effective monitoring of this species is critically important for anuran species generally in south-western Nigeria because anurans are cosmopolitan and timely steps can be taken when severe decline is detected. The population values of these amplectant toads showed that females specimens had higher snout-vent-length (SVL) and weight (WT) values than males (SVLfemale = 8.16±1.12cm, SVLmale = 7.12±0.94cm; WTfemale = 64.55±21.63g, WTmale = 52.15±15.33g) which made it a female-biased SSD species. The females and males differed significantly in the SVL (P<0.05, df=3, tcal = -5.49) and weight (P<0.05, df=3, tcal = -3.21). SSD no doubt is an evolutionary phenomenom exhibited by A. regularis as a means of surviving and propagating their species. Therefore, it is important to note that SSD is a biological and evolutionary necessity.
 
Keywords: Amietophrynus regularis, amplectant, monitoring, anuran, dimorphism and evolutionary